2 male cats, consistent fighting

My cats have had constant fighting since I got them all initiated by the older cat Zeke( 10 yrs old). Zeke was adopted at age 4 from a shelter. He had lived in the shelter his entire life up to that point after being given up as a baby. I imagine that there is something that happens to a cat's psyche after not having a person and being in such an overstimulating environment for so long. When I first got him, he was a lot more aggressive. He would lunge at people and scratch them, but he never does this anymore and is generally very sweet towards humans. His brother; however, is a different story.

Remi is 6 years old. I adopted him from a shelter at age 4. He is very mild mannered and sweet. He tends to be more anxious. When I first introduced them, despite doing the slow introduction method, the fighting was constant. For a second, Remi was scared to use the bathroom, so I put them both on Prozac for cats per vet recommendation. I didn't see much change in the Prozac in Zeke's behavior unfortunately, so I have taken him off of it. Luckily, the bathroom issue has resolved.

Typically, fights start when Remi sits in front of the fridge. Zeke approaches him and "yells" at him constantly until I intervene. I usually will stand in between them, or spray him with a water bottle( i just learned how bad that is, so I won't be doing that anymore! :( ). That usually works for a bit, but most days he just goes back, and I separate them by putting Zeke in "time out" in my room. The other trigger for fights is when Remi is higher up, so the fights are territorial in nature.

I try to distract him by playing which usually works. Zeke has a lot of energy. He likes to do flips and run all around the house when he plays. I suspect part of the reason he yells at his brother is just that he is bored. Occasionally, they will get into big scuffles where Zeke full on attacks Remi. They had a scuffle tn that was really scary. I tried to separate them using a cat scratch tower, but Remi did get some scratches.

It has improved a lot! Zeke used to get mad at Remi when he was in the area while he was playing. Now, Zeke will walk away and give Remi a turn to play while waiting patiently. They are able exist peacefully. They will sleep in the same area or chill and enjoy a breeze, so I feel like there is hope. Part of me is scared that I am being unfair to Remi keeping him in this environment where he has a constant stressor. I love them both so much, it would break my heart to have to re-home one of them.

Any advice to help with the fights would be greatly appreciated. Now that I know the spray bottle isn't the answer, how would you break up fights or stop the yelling without accidentally positively reinforcing the behavior (ie offering a treat)? Is it a good solution to immediately put Zeke in time out? I'd also really appreciate some advice on how to better meet Zeke's stimulation needs. I am in grad school and work, so I do my best to play with him and entertain him, but the yelling is really wearing me down( I can only imagine how poor Remi feels). Most nights, I separate them, so Remi feels like he a consistent time of peace. Is this a bad idea? I always get sad when he eagerly follows me to my door after i've locked Zeke in there with me.

For some context, I am obsessed with these cats. They have 3 cat trees, 2 scratch towers, multiple cozy spots and boxes. They have their own bowls and multiple liter boxes, so theoretically resources shouldn't be a problem. They are also both neutered. Thanks in advance for your thoughts!