Ultron Will Assist Thanos

When Thanos appeared in the mid-credits scene of Avengers: Age of Ultron and said “fine, I’ll do it myself”, it seemed a little out of place. The suggestion was that someone in the movie had failed it, but it certainly wasn’t obvious who.
However, one suggestion is that Ultron was actually Thanos’ plan all along – the Mad Titan had orchestrated a series of events that led to Ultron’s creation, and the robot would work as his agent on Earth to fight the Avengers.
With that in mind, there is a rumour that Thanos will recreate Ultron and bring him back to work as his ally in the Avengers: Infinity War movies – the link with the Sceptre/Mind Stone does actually make the idea feasible as well.
