Context
Our family has four cats. Some details about Pepe, the most relevant one to this question:
- 5 years old
- Orange tabby
- Male
- Exclusively indoors
- Properly fixed
- Extremely friendly and affectionate
Last fall we discovered, fostered, and then adopted a trio of stray kittens. At the time Pepe was scared of these kittens, often hiding in our rooms at the expense of his own well-being. That problem has since been resolved and he now gets along with the triplets very well.
Recently another male cat, whom we'll call T'Challa, has been walking around our neighborhood, including on our front porch. He's friendly, but we otherwise know very little about him; we're not even certain that he's stray.
The Problem
When T'Challa prowls around our yard or our porch, Pepe starts to get very defensive, even trying to attack him through the window. What confuses me is that this is extremely unlike him.
Some more facts about Pepe's behavior:
- He gets riled up to the extent that he'll force the triplets out of his way.
- When he calms down, he's friendly and affectionate again.
- He never behaves this way with the triplets. He plays or cuddles with them all the time.
- He's not ill or in pain.
- Their first interaction was apparently cordial, but I wasn't there so I couldn't tell you much more.
My question: what happened?