From Per Jorner's Nearly Ultimate Fallout 2 Guide:
"Vic may end up in a state known as "apathetic Vic" where he refuses to communicate other than saying "I've had it up to here". This will happen if you inflict damage on him while he's not in your party, but in rare cases it can happen when you hit him with friendly fire even if he is. In v1.0 this was apparently much more likely, but it can happen even with the patch (the patch notes state NPCs will not turn hostile "under most circumstances"). Once he's gone bitter there's no cure for it, so you'll probably have to put him to sleep to get your stuff (or load). It can also happen that he keeps tagging along as an NPC only you can't talk to him."
I googled it for you. Three seconds is all it took.
Ain't that sweet?