diff --git a/src/matrix/Sync.js b/src/matrix/Sync.js
index 62bb67bd..ed9889b1 100644
--- a/src/matrix/Sync.js
+++ b/src/matrix/Sync.js
@@ -333,6 +333,7 @@ export class Sync {
             storeNames.roomState,
             storeNames.roomMembers,
             storeNames.timelineEvents,
+            storeNames.timelineRelations,
             storeNames.timelineFragments,
             storeNames.pendingEvents,
             storeNames.userIdentities,
diff --git a/src/matrix/room/BaseRoom.js b/src/matrix/room/BaseRoom.js
index 9269404a..8df281fd 100644
--- a/src/matrix/room/BaseRoom.js
+++ b/src/matrix/room/BaseRoom.js
@@ -259,6 +259,7 @@ export class BaseRoom extends EventEmitter {
             const txn = await this._storage.readWriteTxn([
                 this._storage.storeNames.pendingEvents,
                 this._storage.storeNames.timelineEvents,
+                this._storage.storeNames.timelineRelations,
                 this._storage.storeNames.timelineFragments,
             ]);
             let extraGapFillChanges;
diff --git a/src/matrix/storage/common.js b/src/matrix/storage/common.js
index bd477cbd..4d10ef65 100644
--- a/src/matrix/storage/common.js
+++ b/src/matrix/storage/common.js
@@ -22,6 +22,7 @@ export const STORE_NAMES = Object.freeze([
     "invites",
     "roomMembers",
     "timelineEvents",
+    "timelineRelations",
     "timelineFragments",
     "pendingEvents",
     "userIdentities",
diff --git a/src/matrix/storage/idb/Transaction.js b/src/matrix/storage/idb/Transaction.js
index a2041d31..bdcc45e3 100644
--- a/src/matrix/storage/idb/Transaction.js
+++ b/src/matrix/storage/idb/Transaction.js
@@ -21,6 +21,7 @@ import {SessionStore} from "./stores/SessionStore.js";
 import {RoomSummaryStore} from "./stores/RoomSummaryStore.js";
 import {InviteStore} from "./stores/InviteStore.js";
 import {TimelineEventStore} from "./stores/TimelineEventStore.js";
+import {TimelineRelationStore} from "./stores/TimelineRelationStore.js";
 import {RoomStateStore} from "./stores/RoomStateStore.js";
 import {RoomMemberStore} from "./stores/RoomMemberStore.js";
 import {TimelineFragmentStore} from "./stores/TimelineFragmentStore.js";
@@ -82,6 +83,10 @@ export class Transaction {
         return this._store("timelineEvents", idbStore => new TimelineEventStore(idbStore));
     }
 
+    get timelineRelations() {
+        return this._store("timelineRelations", idbStore => new TimelineRelationStore(idbStore));
+    }
+
     get roomState() {
         return this._store("roomState", idbStore => new RoomStateStore(idbStore));
     }
diff --git a/src/matrix/storage/idb/schema.js b/src/matrix/storage/idb/schema.js
index 3af31d8d..256b6732 100644
--- a/src/matrix/storage/idb/schema.js
+++ b/src/matrix/storage/idb/schema.js
@@ -16,6 +16,7 @@ export const schema = [
     createInviteStore,
     createArchivedRoomSummaryStore,
     migrateOperationScopeIndex,
+    createTimelineRelationsStore,
 ];
 // TODO: how to deal with git merge conflicts of this array?
 
@@ -135,4 +136,9 @@ async function migrateOperationScopeIndex(db, txn) {
         txn.abort();
         console.error("could not migrate operations", err.stack);
     }
+}
+
+//v10
+function createTimelineRelationsStore(db) {
+    db.createObjectStore("timelineRelations", {keyPath: ""});
 }
\ No newline at end of file
diff --git a/src/matrix/storage/idb/stores/TimelineRelationStore.js b/src/matrix/storage/idb/stores/TimelineRelationStore.js
new file mode 100644
index 00000000..504693f9
--- /dev/null
+++ b/src/matrix/storage/idb/stores/TimelineRelationStore.js
@@ -0,0 +1,62 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+import {MIN_UNICODE, MAX_UNICODE} from "./common.js";
+
+function encodeKey(roomId, targetEventId, relType, sourceEventId) {
+    return `${roomId}|${targetEventId}|${relType}|${sourceEventId}`;
+}
+
+function decodeKey(key) {
+    const [roomId, targetEventId, relType, sourceEventId] = key.split("|");
+    return {roomId, targetEventId, relType, sourceEventId};
+}
+
+export class TimelineRelationStore {
+    constructor(store) {
+        this._store = store;
+    }
+
+    add(roomId, targetEventId, relType, sourceEventId) {
+        return this._store.add(encodeKey(roomId, targetEventId, relType, sourceEventId));
+    }
+
+    remove(roomId, targetEventId, relType, sourceEventId) {
+        return this._store.delete(encodeKey(roomId, targetEventId, relType, sourceEventId));
+    }
+
+    removeAllForTarget(roomId, targetId) {
+        const range = this._store.IDBKeyRange.bound(
+            encodeKey(roomId, targetId, MIN_UNICODE, MIN_UNICODE),
+            encodeKey(roomId, targetId, MAX_UNICODE, MAX_UNICODE),
+            true,
+            true
+        );
+        return this._store.delete(range);
+    }
+
+    async getForTargetAndType(roomId, targetId, relType) {
+        // exclude both keys as they are theoretical min and max,
+        // but we should't have a match for just the room id, or room id with max
+        const range = this._store.IDBKeyRange.bound(
+            encodeKey(roomId, targetId, relType, MIN_UNICODE),
+            encodeKey(roomId, targetId, relType, MAX_UNICODE),
+            true,
+            true
+        );
+        const keys = await this._store.selectAll(range);
+        return keys.map(decodeKey);
+    }
+}