Presumably it’s for training, but when Thor goes up against Iron Man, it could be about anything. The drinking schedule, how untidy the Stark HQ is, whether man can make scientific magic the same way Gods can. There’s a lot to fight about, and the trailers all hint that the Avengers are a time bomb waiting to go off.
In the new clip from The Avengers, Joss Whedon does the kind of playing that most comic book fans have to do with plastic action figures. He pits two titans against each other, turning Robert Downey Jr. and Chris Hemsworth into his playthings. Fortunately one of them has a suit that absorbs lightning.
Check it out for yourself: