So, last year around this time our younger cat, Otis, started being really aggressive to our older cat, Milo. This lasted about a week. We separated them, sedated Otis with clamicalm. And worked with them every night giving treats and slowly bringing them back together. Eventually Otis came around and all was good. A few months later and it happened again. Again we repeated the process. This time it only took a couple days. Last Saturday Otis went after milo again. This marks 3 times in one year he snaps and just hates him. Milo is more timid and kinda just a fat and happy cat. We are trying the same methods again but Otis now won’t take the clamicalm and after 5 days still is hissing at Milo. Only difference now is he isn’t chasing him. We don’t know what to do anymore! Is it possible that these two cats just aren’t meant to be? Can anyone give me some advice?