Hello everyone, I’m hoping to get some advice or reassurance because this has been really stressful.

I have two male cats, Marcel and Willis, who are VERY bonded. They’ve always gotten along great—sleeping together, grooming each other, no history of aggression at all, ever.

They are not “outside cats”, but I occasionally let them out while I do yard work as we live on a farm within a few acres. One day while they were out, Marcel had a close encounter with a fox.

He was not bitten, as I witnessed the whole thing unfold. I scared the fox off and grabbed Marcel. Ever since I brought him back inside, things have been completely off between him and Willis.

I should note that I had just brought Willis back inside so he had no idea what’s got Marcel all worked up. He tried to check on Marcel and he (Marcel) flipped out, understandably. It seemed almost as if he thought Willis was the fox himself. Willis became defensive of course, which did not help the situation. I separated them immediately.

Here we are, 18 days later, and I’m starting to feel hopeless. Willis seems to be over it - he just wants his friend back. Marcel on the other hand, still hates the sight of him. Growls, hisses, screams, you name it.

Admittedly, I shouldn’t have placed Marcel next to Willis like that after such a traumatic experience, but I’ve had cats my whole life and didn’t even know a situation like this could occur.

From what I’ve read, this seems like non-recognition aggression—like Marcel smells different (fox, stress, outside scents), and now everything is off. But could smell still be an issue 2.5 weeks later??

Here’s what I’ve done so far:

- Separated them completely for 3 days (no visual contact)

- They are aware of each other (meowing, pawing at the door)

- Did scent swapping with towels and bedding

- Tried a reintroduction in the same room with treats/toys (this went badly—Marcel got aggressive again)

- Went back to separation and am now doing slow visual reintroduction with a cracked door

- I’ve seen some progress (less intense reactions, brief calm sniffing), but then Marcel still snaps

At this point I’m feeling pretty discouraged and worried I somehow broke their relationship, even though I know that sounds dramatic.

My questions:

- Does this sound like typical non-recognition aggression after a stressful/outdoor incident?

- How long does this usually take to fully resolve?

- Is it normal for one cat (Marcel) to be the only aggressor while the other seems mostly fine?

- Any tips to help Marcel relax and speed this process up?

I’m currently back to slow, controlled reintroductions with a barrier and trying not to rush things.

Any advice or similar experiences would really help—thanks.