my new bad habit: getting passive in position

[Kumubou]

A read would be a huge help here.

If he's aggro, it isn't terrible. You probably should find a raise somewhere... but I'm not quite sure where.

Against a more passive opponent again you should raise somewhere (probably the flop), and I think you can safely raise the river -- odds are he had some kind of pair, and you either just sucked out or you were ahead the whole time. He'll pay off regardless. Folding to a three-bet is probably right if he's passive and predictable, but actually doing that is hard.

-K