Added @AntiTcb's suggestions

src/Discord.Net.Rest/ClientHelper.cs

@@ -156,7 +156,16 @@ namespace Discord.Rest
         public static async Task<IReadOnlyCollection<RestRelationship>> GetRelationshipsAsync(BaseDiscordClient client)
         {
             var models = await client.ApiClient.GetRelationshipsAsync().ConfigureAwait(false);
-            return models.Select(r => RestRelationship.Create(client, r)).ToImmutableArray();
+            return models.Select(r => RestRelationship.Create(client, r)).ToReadOnlyCollection(models);
         }
+
+        public static async Task AddFriendAsync(BaseDiscordClient client, ulong user, RequestOptions options) 
+            => await client.ApiClient.AddFriendAsync(user, options).ConfigureAwait(false);
+
+        public static async Task BlockUserAsync(BaseDiscordClient client, ulong user, RequestOptions options)
+            => await client.ApiClient.BlockUserAsync(user, options).ConfigureAwait(false);
+
+        public static async Task RemoveRelationshipAsync(BaseDiscordClient client, ulong user, RequestOptions options)
+            => await client.ApiClient.RemoveRelationshipAsync(user, options).ConfigureAwait(false);
     }
 }

src/Discord.Net.Rest/Entities/Users/RestUser.cs

@@ -62,13 +62,13 @@ namespace Discord.Rest
 
         public override string ToString() => $"{Username}#{Discriminator}";
         private string DebuggerDisplay => $"{Username}#{Discriminator} ({Id}{(IsBot ? ", Bot" : "")})";
-        
+
         public Task AddFriendAsync(RequestOptions options = null)
-            => Discord.ApiClient.AddFriendAsync(Id, options);
+            => ClientHelper.AddFriendAsync(Discord, Id, options);
         public Task BlockUserAsync(RequestOptions options = null)
-            => Discord.ApiClient.BlockUserAsync(Id, options);
+            => ClientHelper.BlockUserAsync(Discord, Id, options);
         public Task RemoveRelationshipAsync(RequestOptions options = null)
-            => Discord.ApiClient.RemoveRelationshipAsync(Id, options);
+            => ClientHelper.RemoveRelationshipAsync(Discord, Id, options);
 
         //IUser
         async Task<IDMChannel> IUser.GetOrCreateDMChannelAsync(RequestOptions options)

src/Discord.Net.WebSocket/Entities/Users/SocketUser.cs

@@ -65,12 +65,12 @@ namespace Discord.WebSocket
         public override string ToString() => $"{Username}#{Discriminator}";
         private string DebuggerDisplay => $"{Username}#{Discriminator} ({Id}{(IsBot ? ", Bot" : "")})";
         internal SocketUser Clone() => MemberwiseClone() as SocketUser;
-        
+
         public async Task AddFriendAsync(RequestOptions options = null)
-            => await Discord.ApiClient.AddFriendAsync(Id, options);
+            => await ClientHelper.AddFriendAsync(Discord, Id, options);
         public async Task BlockUserAsync(RequestOptions options = null)
-            => await Discord.ApiClient.BlockUserAsync(Id, options);
+            => await ClientHelper.BlockUserAsync(Discord, Id, options);
         public async Task RemoveRelationshipAsync(RequestOptions options = null)
-            => await Discord.ApiClient.RemoveRelationshipAsync(Id, options);
+            => await ClientHelper.RemoveRelationshipAsync(Discord, Id, options);
     }
 }