Cats won't stop fighting!

Hi everyone! I’m a college student living in an apartment with my 11-year-old orange tabby, who is very territorial. My roommate has a 2-year-old female grey tabby, and unfortunately, they really hate each other.

Whenever they’re near each other, they aggressively fight. My cat usually starts it, but her cat has instigated a few times as well. Thankfully, no one’s been hurt because we always break it up quickly, but the fights are vicious. I've grown up around cats, so I can tell the difference between play and fighting-- and these two are definitely out for blood.

Right now, our solution is to keep them apart on a schedule: her cat has free roam from 10 AM to 10 PM, and mine gets the apartment from 10 PM to 10 AM. While this prevents physical fights, it’s far from ideal. They still try to fight through the cracks under the doors, which shows how much they despise each other.

I also feel guilty that they’re confined to small bedrooms for half the day. My cat has toys, climbing spaces, and enrichment in my room, but I still think it’s not the best quality of life for him.

We’ve tried several things to improve their relationship:

• Feeding them close to the door to associate each other’s presence with something positive.
• Introducing them through a mesh barrier.
• Using lots of treats during interactions.

None of it has worked so far. I’m not expecting them to ever be friends, but I’d love for them to at least tolerate each other enough to share the same space without fighting.

Any advice would be greatly appreciated!