T.S.
My son will be 3 next week and he is into the whole superhero thing too. He makes up his own superhero so I never know who he is pretending to be. He tends to go into phases... summertime, everything was fireworks (if it was a flower, it was a firework, if he splashed in the tub, it was a firework....) then fall came and it was all about scarecrows, and now all of a sudden, it's superheroes. I think it's a normal toddler/kid thing. Embrace it and do pretend play with him to get him involved in other things... build his imagination. Like if you take him to the playground, pretend the jungle gym is the batcave.... when you color, say 'lets draw out a map to the bad guys cave (and you can say the Riddler, or Penguin). Go with what he wants to do and play along with him. As long as he is good, well behaved, listens to what he's told and eating, what's the problem?