So I have ex's cat but it is kind of a weird situation. When he had the cat all the cat did was sleep and he was always saying the cat was a pig and a bully to the other cat, which I never saw. But the whole time I dated this guy this cat was just very lazy and did not do much. When I adopted the cat he changed. He now is lively, cuddly, plays with his toy mice and is really lovey dovey. Also, he had ear mites and he was scratching so much that he had scabs behind his ears. Did it sound like my ex didn't treat him very well??
I'm glad you got rid of the guy and kept the cat! He did not give the cat proper vet care at the least. Bring your new #1 guy to the vet and make sure he is up to date on his shots, worm and mite free, and wears a collar with i.d. You can reward him with treats like SmartBites or catnip Greenies, and get a cat condo, toys and scratchers for him. It sounds like the ex's purpose was to hook you up with the cat, and it worked! Congrats on finding a better companion... that purrs. ^_^
It sounds like he didn't spend much time interacting with the cat. It's possible the cat was so lethargic because he didn't feel well. Ear mites can be a very itchy and painful condition.
At the least he did not bond with the cat.