The K Bros
Who are the K Bros?
The Krassenstein brothers.
On nearly every POTUS tweet, they show up as the top few responses and use the space to attack the President. Often they are responses 1-6 right below the original tweet.
IMO they are either bots, using bots, or have some special arrangement with @Jack (Twitter CEO) or Twitter to get top spot access or early alert before the tweet is posted or something.