F+T is the first time I have 2 cats. And they also had a short period of flying fur before they became friends. And since then the fur flies once a week and there has also been some blood - a scratch on tigris head, a little bit in Filou's ear.

I notice that here at PT some kitties seem to come in a period of more stress after 2 weeks or so.

Outside many cats can share the same territory in a kind of time sharing system: this is my path in the morning and your's in the afternoon. If a new cat arrives, there will be some fight before they have developped a new sharing schedule. So even some back gardens can be the territory of quite a number of cats.

I never heard about a cat killing another cat (and especially not of a fixed cat killing another fixed cat) but I understand how you must feel.

How is their behavior after a fight? More peaceful for a certain time? Who attacks first?

I wish I could be more helpful