Originally Posted by Tony Stark
I really don't want Ultron to be a corrupted Jarvis, other than what I speculated on, in that Tony was working on an AI system for the military, and they dumped the project, and he took the work that they did and made J.A.R.V.I.S. and based the A.I. on his father's butler. The military took what Tony was doing and corrupted it.
I am hoping that Jarvis becomes Ultron because the best villains, like Stane and Loki, are those that have a deep personal connection to their nemesis. With Pym out of the picture (though I am hoping Whedon has Pym collaborating with Stark on the Jarvis AI), the Stark/Jarvis relationship is a terrific one to exploit. It will be quite chilling to have the voice of Paul Bettany coming out of a killer robot.
Whedon mentioned that Ultron will be going through upgrades during the film, so while he will start out with a transformed Iron Man suit, I think he's eventually going to end up in the big guy - the Destroyer armor. From the Avengers preview comics we know the SHIELD has the armor, and having Jarvis/Ulton transfer his conscious into this form is a much "cleaner" path to take than having him create a body from scratch. Indestructible armor is very difficult to come by, and SHIELD having one that somewhat resembles Ultron's comic book dimensions may be too convenient to pass up.