I've been calling the cat-with-no-name "Beau", which rhymes with "NO!"
Some days, Finn and Beau get along fine. Other times, I think Finn is going to kill Beau, pinning him to the floor and administering some punishing bites. And yet, Beau keeps coming back for more.
Beau is an indoor cat, so Finn gets respite by going out most nights. I put them in separate parts of the house when I am going out. But I wonder what will happen when Beau reaches his full size.