Do yourself and Tinky & Jupiter a favor and go and get the little guy combo tested for FeLV/FIV if he's not been tested yet. Even if he's isolated in your house.

You wouldn't want to risk infecting you cats with these two deadlies.

I'm happy he ate. he should go on the KMR (mix it with canned food and water), for nutrition sake, even though he's eating other things.