diff --git a/fastpair/internal/BUILD b/fastpair/internal/BUILD
index dc0714cf..17785dc7 100644
--- a/fastpair/internal/BUILD
+++ b/fastpair/internal/BUILD
@@ -19,6 +19,7 @@ cc_library(
         "//fastpair/scanning:scanner",
         "//internal/platform:types",
         "@com_google_absl//absl/status",
+        "@com_google_absl//absl/strings:str_format",
     ],
 )
 
@@ -30,6 +31,7 @@ cc_test(
     ],
     deps = [
         ":internal",
+        "//fastpair/message_stream:fake_gatt_callbacks",
         "//fastpair/message_stream:fake_provider",
         "//fastpair/server_access:test_support",
         "//internal/platform:test_util",
diff --git a/fastpair/internal/fast_pair_seeker_impl.cc b/fastpair/internal/fast_pair_seeker_impl.cc
index 79259e15..a9a817ce 100644
--- a/fastpair/internal/fast_pair_seeker_impl.cc
+++ b/fastpair/internal/fast_pair_seeker_impl.cc
@@ -20,6 +20,7 @@
 #include <utility>
 
 #include "absl/status/status.h"
+#include "absl/strings/str_format.h"
 #include "fastpair/fast_pair_events.h"
 #include "fastpair/pairing/pairer_broker_impl.h"
 #include "fastpair/scanning/scanner_broker_impl.h"
@@ -36,10 +37,23 @@ FastPairSeekerImpl::FastPairSeekerImpl(ServiceCallbacks callbacks,
   pairer_broker_->AddObserver(this);
 }
 
+FastPairSeekerImpl::~FastPairSeekerImpl() {
+  pairer_broker_->RemoveObserver(this);
+  FinishPairing(absl::AbortedError("Pairing terminated"));
+  DestroyOnExecutor(std::move(pairer_broker_), executor_);
+}
+
 absl::Status FastPairSeekerImpl::StartInitialPairing(
     const FastPairDevice& device, const InitialPairingParam& params,
     PairingCallback callback) {
-  return absl::UnimplementedError("StartInitialPairing");
+  if (pairer_broker_->IsPairing()) {
+    return absl::AlreadyExistsError("Already pairing");
+  }
+
+  pairing_callback_ = std::make_unique<PairingCallback>(std::move(callback));
+  device_under_pairing_ = &const_cast<FastPairDevice&>(device);
+  pairer_broker_->PairDevice(*device_under_pairing_);
+  return absl::OkStatus();
 }
 
 absl::Status FastPairSeekerImpl::StartSubsequentPairing(
@@ -84,6 +98,9 @@ void FastPairSeekerImpl::OnDeviceFound(FastPairDevice& device) {
 // ScannerBroker::Observer::OnDeviceLost
 void FastPairSeekerImpl::OnDeviceLost(FastPairDevice& device) {
   NEARBY_LOGS(INFO) << "Device lost: " << device;
+  if (IsDeviceUnderPairing(device)) {
+    FinishPairing(absl::UnavailableError("Device lost during pairing"));
+  }
 }
 
 // PairerBroker:Observer::OnDevicePaired
@@ -109,6 +126,11 @@ void FastPairSeekerImpl::OnAccountKeyWrite(FastPairDevice& device,
 // PairerBroker:Observer::OnPairingComplete
 void FastPairSeekerImpl::OnPairingComplete(FastPairDevice& device) {
   NEARBY_LOGS(INFO) << __func__ << ": " << device;
+  if (!IsDeviceUnderPairing(device)) {
+    NEARBY_LOGS(WARNING) << "unexpected on pair complete callback";
+    return;
+  }
+  FinishPairing(absl::OkStatus());
 }
 
 // PairerBroker:Observer::OnPairFailure
@@ -116,6 +138,24 @@ void FastPairSeekerImpl::OnPairFailure(FastPairDevice& device,
                                        PairFailure failure) {
   NEARBY_LOGS(INFO) << __func__ << ": " << device
                     << " with PairFailure: " << failure;
+  if (!IsDeviceUnderPairing(device)) {
+    NEARBY_LOGS(WARNING) << "unexpected on pair failure callback";
+    return;
+  }
+  FinishPairing(
+      absl::InternalError(absl::StrFormat("Pairing failed with %v", failure)));
+}
+
+bool FastPairSeekerImpl::IsDeviceUnderPairing(const FastPairDevice& device) {
+  return device_under_pairing_ == &device;
+}
+
+void FastPairSeekerImpl::FinishPairing(absl::Status result) {
+  if (pairing_callback_ && device_under_pairing_ != nullptr) {
+    pairing_callback_->on_pairing_result(*device_under_pairing_, result);
+  }
+  pairing_callback_.reset();
+  device_under_pairing_ = nullptr;
 }
 
 void FastPairSeekerImpl::SetIsScreenLocked(bool locked) {
diff --git a/fastpair/internal/fast_pair_seeker_impl.h b/fastpair/internal/fast_pair_seeker_impl.h
index 5a9c2513..60d0164b 100644
--- a/fastpair/internal/fast_pair_seeker_impl.h
+++ b/fastpair/internal/fast_pair_seeker_impl.h
@@ -22,7 +22,7 @@
 #include "fastpair/fast_pair_events.h"
 #include "fastpair/fast_pair_seeker.h"
 #include "fastpair/internal/mediums/mediums.h"
-#include "fastpair/pairing/pairer_broker.h"
+#include "fastpair/pairing/pairer_broker_impl.h"
 #include "fastpair/repository/fast_pair_device_repository.h"
 #include "fastpair/scanning/scanner_broker_impl.h"
 #include "internal/platform/single_thread_executor.h"
@@ -58,6 +58,8 @@ class FastPairSeekerImpl : public FastPairSeekerExt,
   FastPairSeekerImpl(ServiceCallbacks callbacks, SingleThreadExecutor* executor,
                      FastPairDeviceRepository* devices);
 
+  ~FastPairSeekerImpl() override;
+
   // From FastPairSeeker.
   absl::Status StartInitialPairing(const FastPairDevice& device,
                                    const InitialPairingParam& params,
@@ -92,6 +94,8 @@ class FastPairSeekerImpl : public FastPairSeekerExt,
   void OnPairFailure(FastPairDevice& device, PairFailure failure) override;
 
   void InvalidateScanningState() ABSL_EXCLUSIVE_LOCKS_REQUIRED(*executor_);
+  bool IsDeviceUnderPairing(const FastPairDevice& device);
+  void FinishPairing(absl::Status result);
 
   ServiceCallbacks callbacks_;
   SingleThreadExecutor* executor_;
@@ -99,7 +103,9 @@ class FastPairSeekerImpl : public FastPairSeekerExt,
   Mediums mediums_;
   std::unique_ptr<ScannerBrokerImpl> scanner_;
   std::unique_ptr<ScannerBrokerImpl::ScanningSession> scanning_session_;
-  std::unique_ptr<PairerBroker> pairer_broker_;
+  std::unique_ptr<PairerBrokerImpl> pairer_broker_;
+  std::unique_ptr<PairingCallback> pairing_callback_;
+  FastPairDevice* device_under_pairing_ = nullptr;
   FastPairDevice* test_device_ = nullptr;
   bool is_screen_locked_ = false;
 };
diff --git a/fastpair/internal/fast_pair_seeker_impl_test.cc b/fastpair/internal/fast_pair_seeker_impl_test.cc
index db6c2337..16288d80 100644
--- a/fastpair/internal/fast_pair_seeker_impl_test.cc
+++ b/fastpair/internal/fast_pair_seeker_impl_test.cc
@@ -23,6 +23,8 @@
 #include "protobuf-matchers/protocol-buffer-matchers.h"
 #include "gtest/gtest.h"
 #include "absl/time/clock.h"
+#include "absl/time/time.h"
+#include "fastpair/message_stream/fake_gatt_callbacks.h"
 #include "fastpair/message_stream/fake_provider.h"
 #include "fastpair/server_access/fake_fast_pair_repository.h"
 #include "internal/platform/count_down_latch.h"
@@ -36,9 +38,13 @@ constexpr absl::string_view kServiceID{"Fast Pair"};
 constexpr absl::string_view kFastPairServiceUuid{
     "0000FE2C-0000-1000-8000-00805F9B34FB"};
 constexpr absl::string_view kModelId{"718c17"};
-constexpr absl::string_view kPublicAntiSpoof =
-    "Wuyr48lD3txnUhGiMF1IfzlTwRxxe+wMB1HLzP+"
-    "0wVcljfT3XPoiy1fntlneziyLD5knDVAJSE+RM/zlPRP/Jg==";
+constexpr absl::string_view kBobPrivateKey =
+    "02B437B0EDD6BBD429064A4E529FCBF1C48D0D624924D592274B7ED81193D763";
+constexpr absl::string_view kBobPublicKey =
+    "F7D496A62ECA416351540AA343BC690A6109F551500666B83B1251FB84FA2860795EBD63D3"
+    "B8836F44A9A3E28BB34017E015F5979305D849FDF8DE10123B61D2";
+constexpr absl::string_view kPasskey = "123456";
+
 constexpr absl::Duration kTaskWaitTimeout = absl::Milliseconds(100);
 
 using ::testing::status::StatusIs;
@@ -52,7 +58,8 @@ class MediumEnvironmentStarter {
 class FastPairSeekerImplTest : public testing::Test {
  protected:
   void SetUp() override {
-    repository_ = FakeFastPairRepository::Create(kModelId, kPublicAntiSpoof);
+    repository_ = FakeFastPairRepository::Create(
+        kModelId, absl::HexStringToBytes(kBobPublicKey));
   }
 
   void TearDown() override { executor_.Shutdown(); }
@@ -62,6 +69,7 @@ class FastPairSeekerImplTest : public testing::Test {
   FastPairDeviceRepository devices_{&executor_};
   std::unique_ptr<FakeFastPairRepository> repository_;
   std::unique_ptr<FastPairSeekerImpl> fast_pair_seeker_;
+  FakeGattCallbacks fake_gatt_callbacks_;
 };
 
 TEST_F(FastPairSeekerImplTest, StartAndStopFastPairScan) {
@@ -136,6 +144,46 @@ TEST_F(FastPairSeekerImplTest, ScreenLocksDuringAdvertising) {
   EXPECT_FALSE(latch.Await(kTaskWaitTimeout).result());
 }
 
+TEST_F(FastPairSeekerImplTest, InitialPairing) {
+  NEARBY_LOG_SET_SEVERITY(VERBOSE);
+  FakeProvider provider;
+  CountDownLatch discover_latch(1);
+  CountDownLatch pair_latch(1);
+  fast_pair_seeker_ = std::make_unique<FastPairSeekerImpl>(
+      FastPairSeekerImpl::ServiceCallbacks{
+          .on_initial_discovery =
+              [&](const FastPairDevice& device, InitialDiscoveryEvent event) {
+                EXPECT_EQ(device.GetModelId(), kModelId);
+                EXPECT_OK(fast_pair_seeker_->StartInitialPairing(
+                    device, {},
+                    {.on_pairing_result = [&](const FastPairDevice& device,
+                                              absl::Status status) {
+                      EXPECT_EQ(device.GetBleAddress(),
+                                provider.GetMacAddress());
+                      EXPECT_OK(status);
+                      pair_latch.CountDown();
+                    }}));
+                discover_latch.CountDown();
+              }},
+      &executor_, &devices_);
+
+  EXPECT_OK(fast_pair_seeker_->StartFastPairScan());
+  provider.PrepareForInitialPairing(
+      {
+          .private_key = absl::HexStringToBytes(kBobPrivateKey),
+          .public_key = absl::HexStringToBytes(kBobPublicKey),
+          .model_id = std::string(kModelId),
+          .pass_key = std::string(kPasskey),
+      },
+      &fake_gatt_callbacks_);
+
+  discover_latch.Await();
+  pair_latch.Await();
+  auto fp_device = devices_.FindDevice(provider.GetMacAddress());
+  ASSERT_TRUE(fp_device.has_value());
+  EXPECT_EQ(provider.GetAccountKey(), fp_device.value()->GetAccountKey());
+}
+
 }  // namespace
 }  // namespace fastpair
 }  // namespace nearby
diff --git a/fastpair/message_stream/BUILD b/fastpair/message_stream/BUILD
index ec145129..41969904 100644
--- a/fastpair/message_stream/BUILD
+++ b/fastpair/message_stream/BUILD
@@ -55,6 +55,7 @@ cc_library(
         "//fastpair:__subpackages__",
     ],
     deps = [
+        ":fake_gatt_callbacks",
         ":message_stream",
         "//fastpair/common",
         "//internal/platform:base",
@@ -87,6 +88,7 @@ cc_library(
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
+        "@com_google_absl//absl/strings",
     ],
 )
 
diff --git a/fastpair/message_stream/fake_gatt_callbacks.h b/fastpair/message_stream/fake_gatt_callbacks.h
index 3ad975ba..f2e6fbda 100644
--- a/fastpair/message_stream/fake_gatt_callbacks.h
+++ b/fastpair/message_stream/fake_gatt_callbacks.h
@@ -21,6 +21,7 @@
 #include "absl/container/flat_hash_map.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/escaping.h"
 #include "internal/platform/ble_v2.h"
 #include "internal/platform/future.h"
 
@@ -43,14 +44,22 @@ class FakeGattCallbacks {
     // characteristic
     absl::StatusOr<std::string> read_value =
         absl::FailedPreconditionError("characteristic not set");
-    absl::AnyInvocable<absl::Status(absl::string_view)> write_callback =
-        [&](absl::string_view data) {
-          write_value.Set(std::string(data));
-          return write_result;
-        };
-    absl::AnyInvocable<absl::StatusOr<std::string>()> read_callback = [&]() {
+    absl::AnyInvocable<absl::Status(absl::string_view)> write_callback;
+    absl::AnyInvocable<absl::StatusOr<std::string>()> read_callback;
+
+    absl::Status WriteCallback(absl::string_view data) {
+      if (write_callback) {
+        return write_callback(data);
+      }
+      write_value.Set(std::string(data));
+      return write_result;
+    }
+    absl::StatusOr<std::string> ReadCallback() {
+      if (read_callback) {
+        return read_callback();
+      }
       return read_value;
-    };
+    }
   };
 
   BleV2Medium::ServerGattConnectionCallback GetGattCallback() {
@@ -65,7 +74,7 @@ class FakeGattCallbacks {
                 callback(absl::NotFoundError("characteristic not found"));
                 return;
               }
-              callback(it->second.read_callback());
+              callback(it->second.ReadCallback());
             },
         .on_characteristic_write_cb =
             [&](const api::ble_v2::BlePeripheral& remote_device,
@@ -78,7 +87,7 @@ class FakeGattCallbacks {
                 callback(absl::NotFoundError("characteristic not found"));
                 return;
               }
-              callback(it->second.write_callback(data));
+              callback(it->second.WriteCallback(data));
             }};
   }
 
diff --git a/fastpair/message_stream/fake_provider.cc b/fastpair/message_stream/fake_provider.cc
index 9fa0dda8..4116ba13 100644
--- a/fastpair/message_stream/fake_provider.cc
+++ b/fastpair/message_stream/fake_provider.cc
@@ -18,7 +18,9 @@
 
 #include "absl/status/status.h"
 #include "absl/strings/escaping.h"
+#include "absl/strings/numbers.h"
 #include "fastpair/common/constant.h"
+#include "internal/platform/medium_environment.h"
 #include <openssl/base.h>
 #include <openssl/bn.h>
 #include <openssl/ec_key.h>
@@ -28,6 +30,10 @@ namespace fastpair {
 
 namespace {
 
+constexpr uint8_t kKeyBasedPairingResponseCode = 1;
+constexpr uint8_t kSeekerPasskeyResponseCode = 2;
+constexpr uint8_t kProviderPasskeyResponseCode = 3;
+
 static EC_POINT *load_public_key(absl::string_view public_key) {
   CHECK_EQ(public_key.size(), kPublicKeyByteSize);
   BN_CTX *bn_ctx;
@@ -129,22 +135,22 @@ void FakeProvider::LoadAntiSpoofingKey(absl::string_view private_key,
 }
 
 std::string FakeProvider::DecryptKbpRequest(absl::string_view request) {
-  NEARBY_LOGS(INFO) << "Encrypted KBP request "
-                    << absl::BytesToHexString(request);
+  NEARBY_LOGS(VERBOSE) << "Encrypted KBP request "
+                       << absl::BytesToHexString(request);
   CHECK_EQ(request.size(), kEncryptedDataByteSize + kPublicKeyByteSize);
   absl::string_view encrypted = request.substr(0, kEncryptedDataByteSize);
   absl::string_view remote_public_key =
       request.substr(kEncryptedDataByteSize, kPublicKeyByteSize);
   std::string shared_secret = CreateSharedSecret(remote_public_key);
   std::string decrypted = Aes128Decrypt(encrypted, shared_secret);
-  NEARBY_LOGS(INFO) << "Decrypted KBP request "
-                    << absl::BytesToHexString(decrypted);
-  account_key_ = shared_secret;
+  NEARBY_LOGS(VERBOSE) << "Decrypted KBP request "
+                       << absl::BytesToHexString(decrypted);
+  shared_secret_ = shared_secret;
   return decrypted;
 }
 
 std::string FakeProvider::Encrypt(absl::string_view data) {
-  return Aes128Encrypt(data, account_key_);
+  return Aes128Encrypt(data, shared_secret_);
 }
 
 std::string FakeProvider::GenSec256r1Secret(
@@ -199,9 +205,9 @@ std::string FakeProvider::CreateSharedSecret(
       Crypto::Sha256(secret).AsStringView().substr(0, kAccountKeySize));
 }
 
-void FakeProvider::StartGattServer(
-    BleV2Medium::ServerGattConnectionCallback callback) {
-  gatt_server_ = ble_.StartGattServer(std::move(callback));
+void FakeProvider::StartGattServer(FakeGattCallbacks *fake_gatt_callbacks) {
+  fake_gatt_callbacks_ = fake_gatt_callbacks;
+  gatt_server_ = ble_.StartGattServer(fake_gatt_callbacks_->GetGattCallback());
 }
 
 absl::Status FakeProvider::NotifyKeyBasedPairing(ByteArray response) {
@@ -211,8 +217,16 @@ absl::Status FakeProvider::NotifyKeyBasedPairing(ByteArray response) {
                                                    false, response);
 }
 
+absl::Status FakeProvider::NotifyPasskey(ByteArray response) {
+  CHECK_NE(gatt_server_, nullptr);
+  CHECK(passkey_characteristic_.has_value());
+  return gatt_server_->NotifyCharacteristicChanged(*passkey_characteristic_,
+                                                   false, response);
+}
+
 void FakeProvider::StartDiscoverableAdvertisement(absl::string_view model_id) {
   advertising_ = true;
+  model_id_ = model_id;
   ble_v1_.StartAdvertising(std::string(kServiceID),
                            ByteArray(absl::HexStringToBytes(model_id)),
                            std::string(kFastPairServiceUuid));
@@ -225,5 +239,101 @@ void FakeProvider::StopAdvertising() {
   }
 }
 
+void FakeProvider::SetKeyBasedPairingCallback() {
+  CHECK_NE(fake_gatt_callbacks_, nullptr);
+  CHECK(key_based_characteristic_.has_value());
+  fake_gatt_callbacks_->characteristics_[*key_based_characteristic_]
+      .write_callback = [this](absl::string_view request) {
+    NEARBY_LOGS(VERBOSE) << "Encrypted request: "
+                         << absl::BytesToHexString(request);
+    std::string decrypted_request = DecryptKbpRequest(request);
+    NEARBY_LOGS(VERBOSE) << "KBP decrypted request "
+                         << absl::BytesToHexString(decrypted_request);
+    fake_gatt_callbacks_->characteristics_[*key_based_characteristic_]
+        .write_value.Set(std::string(decrypted_request));
+    std::string response;
+    response.push_back(kKeyBasedPairingResponseCode);
+    response.append(GetMacAddressAsBytes());
+    response.resize(kEncryptedDataByteSize, 0);
+    absl::Status status = NotifyKeyBasedPairing(ByteArray(Encrypt(response)));
+    NEARBY_LOGS(VERBOSE) << "KBP notify result: " << status;
+    return absl::OkStatus();
+  };
+}
+
+void FakeProvider::SetPasskeyCallback() {
+  CHECK_NE(fake_gatt_callbacks_, nullptr);
+  CHECK(passkey_characteristic_.has_value());
+  fake_gatt_callbacks_->characteristics_[*passkey_characteristic_]
+      .write_callback = [this](absl::string_view request) {
+    NEARBY_LOGS(VERBOSE) << "Passkey Encrypted request: "
+                         << absl::BytesToHexString(request);
+    std::string decrypted = Aes128Decrypt(request, shared_secret_);
+    NEARBY_LOGS(VERBOSE) << "Passkey decrypted request "
+                         << absl::BytesToHexString(decrypted);
+    fake_gatt_callbacks_->characteristics_[*passkey_characteristic_]
+        .write_value.Set(std::string(decrypted));
+    if (decrypted[0] != kSeekerPasskeyResponseCode) {
+      return absl::InvalidArgumentError(
+          absl::StrFormat("Invalid passkey response code: 0x%x", decrypted[0]));
+    }
+
+    std::string response;
+    response.push_back(kProviderPasskeyResponseCode);
+    response.push_back(pass_key_ >> 16);
+    response.push_back(pass_key_ >> 8);
+    response.push_back(pass_key_);
+    response.resize(kEncryptedDataByteSize, 0);
+    absl::Status status = NotifyPasskey(ByteArray(Encrypt(response)));
+    NEARBY_LOGS(VERBOSE) << "Passkey notify result: " << status;
+    return absl::OkStatus();
+  };
+}
+
+void FakeProvider::SetAccountkeyCallback() {
+  CHECK_NE(fake_gatt_callbacks_, nullptr);
+  CHECK(accountkey_characteristic_.has_value());
+  fake_gatt_callbacks_->characteristics_[*accountkey_characteristic_]
+      .write_callback = [this](absl::string_view request) {
+    NEARBY_LOGS(VERBOSE) << "Account key encrypted request: "
+                         << absl::BytesToHexString(request);
+    std::string decrypted = Aes128Decrypt(request, shared_secret_);
+    NEARBY_LOGS(VERBOSE) << "Account key decrypted request "
+                         << absl::BytesToHexString(decrypted);
+    fake_gatt_callbacks_->characteristics_[*accountkey_characteristic_]
+        .write_value.Set(std::string(decrypted));
+
+    account_key_ = AccountKey(decrypted);
+    return absl::OkStatus();
+  };
+}
+
+void FakeProvider::ConfigurePairingContext(absl::string_view pass_key) {
+  api::PairingParams pairing_params;
+  pairing_params.pairing_type =
+      api::PairingParams::PairingType::kConfirmPasskey;
+  pairing_params.passkey = pass_key;
+  auto device = MediumEnvironment::Instance().FindBluetoothDevice(
+      provider_medium_.GetMacAddress());
+  CHECK_NE(device, nullptr);
+  MediumEnvironment::Instance().ConfigBluetoothPairingContext(device,
+                                                              pairing_params);
+  CHECK(absl::SimpleAtoi(pass_key, &pass_key_));
+}
+
+void FakeProvider::PrepareForInitialPairing(
+    PairingConfig config, FakeGattCallbacks *fake_gatt_callbacks) {
+  LoadAntiSpoofingKey(config.private_key, config.public_key);
+  StartGattServer(fake_gatt_callbacks);
+  InsertCorrectGattCharacteristics();
+  SetKeyBasedPairingCallback();
+  SetPasskeyCallback();
+  SetAccountkeyCallback();
+  provider_adapter_.SetScanMode(
+      BluetoothAdapter::ScanMode::kConnectableDiscoverable);
+  ConfigurePairingContext(config.pass_key);
+  StartDiscoverableAdvertisement(config.model_id);
+}
+
 }  // namespace fastpair
 }  // namespace nearby
diff --git a/fastpair/message_stream/fake_provider.h b/fastpair/message_stream/fake_provider.h
index 56ae730e..7813cb5b 100644
--- a/fastpair/message_stream/fake_provider.h
+++ b/fastpair/message_stream/fake_provider.h
@@ -28,8 +28,10 @@
 #include "absl/strings/escaping.h"
 #include "absl/time/clock.h"
 #include "absl/time/time.h"
+#include "fastpair/common/account_key.h"
 #include "fastpair/common/constant.h"
 #include "fastpair/common/fast_pair_device.h"
+#include "fastpair/message_stream/fake_gatt_callbacks.h"
 #include "fastpair/message_stream/message.h"
 #include "internal/platform/ble.h"
 #include "internal/platform/ble_v2.h"
@@ -71,8 +73,18 @@ class FakeProvider {
  public:
   using KeyBasedPairingCallback =
       absl::AnyInvocable<std::string(absl::string_view)>;
+  struct PairingConfig {
+    std::string private_key;  // binary, private Anti-Spoofing Key
+    std::string public_key;   // binary, public Anti-Spoofing Key
+    std::string model_id;
+    std::string pass_key;
+  };
   ~FakeProvider() { Shutdown(); }
 
+  // Sets the fake provider up for initial pairing
+  void PrepareForInitialPairing(PairingConfig config,
+                                FakeGattCallbacks* fake_gatt_callbacks);
+
   void Shutdown() {
     StopAdvertising();
     provider_thread_.Shutdown();
@@ -151,25 +163,31 @@ class FakeProvider {
         BluetoothUtils::FromString(provider_adapter_.GetMacAddress()));
   }
 
-  void StartGattServer(BleV2Medium::ServerGattConnectionCallback callback);
+  void StartGattServer(FakeGattCallbacks* fake_gatt_callbacks);
 
   void InsertCorrectGattCharacteristics() {
+    CHECK_NE(fake_gatt_callbacks_, nullptr);
+
     key_based_characteristic_ = gatt_server_->CreateCharacteristic(
         kFastPairServiceUuid, kKeyBasedCharacteristicUuidV2, permissions_,
         properties_);
     CHECK(key_based_characteristic_.has_value());
+    fake_gatt_callbacks_->characteristics_[*key_based_characteristic_]
+        .write_result = absl::OkStatus();
 
     passkey_characteristic_ = gatt_server_->CreateCharacteristic(
         kFastPairServiceUuid, kPasskeyCharacteristicUuidV2, permissions_,
         properties_);
-
     CHECK(passkey_characteristic_.has_value());
+    fake_gatt_callbacks_->characteristics_[*passkey_characteristic_]
+        .write_result = absl::OkStatus();
 
     accountkey_characteristic_ = gatt_server_->CreateCharacteristic(
         kFastPairServiceUuid, kAccountKeyCharacteristicUuidV2, permissions_,
         properties_);
-
     CHECK(accountkey_characteristic_.has_value());
+    fake_gatt_callbacks_->characteristics_[*accountkey_characteristic_]
+        .write_result = absl::OkStatus();
   }
 
   void LoadAntiSpoofingKey(absl::string_view private_key,
@@ -179,14 +197,20 @@ class FakeProvider {
   std::string Encrypt(absl::string_view data);
 
   absl::Status NotifyKeyBasedPairing(ByteArray response);
+  absl::Status NotifyPasskey(ByteArray response);
 
   void StartDiscoverableAdvertisement(absl::string_view model_id);
   void StopAdvertising();
+  void ConfigurePairingContext(absl::string_view pass_key);
+  AccountKey& GetAccountKey() { return account_key_; }
   std::optional<GattCharacteristic> key_based_characteristic_;
   std::optional<GattCharacteristic> passkey_characteristic_;
   std::optional<GattCharacteristic> accountkey_characteristic_;
 
  private:
+  void SetKeyBasedPairingCallback();
+  void SetPasskeyCallback();
+  void SetAccountkeyCallback();
   std::string GenSec256r1Secret(absl::string_view remote_party_public_key);
   std::string CreateSharedSecret(absl::string_view remote_public_key);
   BluetoothAdapter provider_adapter_;
@@ -201,8 +225,12 @@ class FakeProvider {
   Permission permissions_ = Permission::kWrite;
   std::unique_ptr<EVP_PKEY, void (*)(EVP_PKEY*)> anti_spoofing_key_{
       nullptr, EVP_PKEY_free};
-  std::string account_key_;
+  std::string shared_secret_;
   SingleThreadExecutor provider_thread_;
+  std::string model_id_;
+  FakeGattCallbacks* fake_gatt_callbacks_ = nullptr;
+  unsigned int pass_key_;
+  AccountKey account_key_;
 };
 
 }  // namespace fastpair
diff --git a/fastpair/retroactive/retroactive_test.cc b/fastpair/retroactive/retroactive_test.cc
index 9c126cec..65406496 100644
--- a/fastpair/retroactive/retroactive_test.cc
+++ b/fastpair/retroactive/retroactive_test.cc
@@ -55,7 +55,7 @@ class RetroactiveTest : public testing::Test {
 
     provider_.DiscoverProvider(seeker_medium);
     remote_device_ = seeker_medium.GetRemoteDevice(provider_.GetMacAddress());
-    provider_.StartGattServer(gatt_callbacks_.GetGattCallback());
+    provider_.StartGattServer(&gatt_callbacks_);
     provider_.InsertCorrectGattCharacteristics();
     ASSERT_TRUE(remote_device_.IsValid());
   }
diff --git a/fastpair/server_access/fake_fast_pair_repository.cc b/fastpair/server_access/fake_fast_pair_repository.cc
index 38fc6e7c..e2c501d5 100644
--- a/fastpair/server_access/fake_fast_pair_repository.cc
+++ b/fastpair/server_access/fake_fast_pair_repository.cc
@@ -46,11 +46,17 @@ void FakeFastPairRepository::GetDeviceMetadata(
 
 std::unique_ptr<FakeFastPairRepository> FakeFastPairRepository::Create(
     absl::string_view model_id, absl::string_view public_anti_spoof_key) {
-  std::string decoded_key;
-  absl::Base64Unescape(public_anti_spoof_key, &decoded_key);
   proto::Device metadata;
   auto repository = std::make_unique<FakeFastPairRepository>();
-  metadata.mutable_anti_spoofing_key_pair()->set_public_key(decoded_key);
+  if (public_anti_spoof_key.length() == kPublicKeyByteSize) {
+    metadata.mutable_anti_spoofing_key_pair()->set_public_key(
+        public_anti_spoof_key);
+  } else {
+    std::string decoded_key;
+    absl::Base64Unescape(public_anti_spoof_key, &decoded_key);
+    CHECK_EQ(decoded_key.length(), kPublicKeyByteSize);
+    metadata.mutable_anti_spoofing_key_pair()->set_public_key(decoded_key);
+  }
   repository->SetFakeMetadata(model_id, metadata);
   return repository;
 }