My boy Bob was about four or five months old when I managed to entice him indoors from the backyard. He spent several weeks hiding in his own room (with me spending lots of time sitting on the floor talking to him) before he finally decided that he wanted to join the rest of the family. He's still very skittish (just ask Dr. Goodnow), and he'll never be a lap cat, but he's such a sweet guy! I just let him do his own thing. He gets plenty of pets whenever he asks for them, although frankly he's more fond of Hagrid than he is of me.

The key with ex-ferals, I think, is patience and not expecting too much from them. If Bobby is sitting with you and giving headbumpies, you've already made great progress! He'll hide less and come out and explore more as he gets more comfortable.

As for Billy, even kitties who have always been house pets can be shy. My Angel is a case in point. He was born in my house and has been cuddled from day one, but he acts as though he's never seen a human before. Again, I'd just be patient. He'll figure out soon enough that it's as safe to come looking for pets during the day as it is at night.