Unless it's a wild cat, which I haven't seen, no one nearby has cats here. They don't want to come on my property anyway,You need to get some pictures and movies of Baby Jay. your stories are amazing. What a character he is.
You are probably right about him clashing with another bird. I think blue jays are territorial also. At least they act that way at my feeders. They are always pecking at one another and chasing off the other birds. Maybe his wing got hurt that way or maybe he had a run in with a cat? Got his wing grabbed and wrenched.
That might make him decide that in the house is better than outside.
Oh, I remembered something now.... no more egg hatching, no more egg hatching, no more egg hatching.. I must resist, I must resist. Bandit's ladies are laying the most beautiful little brown eggs ever. If indeed he has the blue gene, then the offspring could very well be olive eggers... but NO MORE HATCHING! At least this year.