bodhi theory - spoilers
my theory is that Bodhi knew exactly who Utah was and why he was there as soon as he saw Tyler teaching him to surf.
It would explain his instant acceptance of Utah in to his previously close-knit group, it would explain him coming to his rescue at Latigo beach - he may even have been tailing him and that's why he so conveniently showed up. Most of all it would explain why, during the discussion about Warchild's gang, Bodhi didn't blink when Utah said "what kind of stuff? Illegal stuff" - the most obvious undercover cop thing an undercover could say.
Bodhi was a thrillseeker so it makes sense that he'd have got off on having AN F . B . I . AGENT around and being able to turn the very person who was supposed to stop him into one of them. Talk about the ultimate ride