I have two cats, Ringo and Milo. Ringo we adopted when he was about a year and 6 months old. After about a few months, we adopted Milo and he was only 4 months at the time. We introduced them slowly keeping them in separate rooms for a few days and eventually they met a got along pretty well. They would play fight and seemed to enjoy each others company.
As Milo got older and bigger, he continued the same level of play fighting. The only difference is that he outgrew Ringo. Two years since adopting Milo, he currently sits at a solid 14lbs while Ringo is only 8lbs. I feel as if Milo knows that he is bigger and uses his size as an advantage. He would push Ringo out the way if he wants to get to where Ringo is sitting and when they play, Milo would just lay his whole body on top of Ringo to limit his movement. We tried to discourage this behavior as Milo aged but it seems to have gotten worse over time especially after my husband and I moved out of our apartment into our first house.
My husband describes Milos behaviour as kitten like and jokes about how he doesnt know how to be his own cat. He constantly wants to play with Ringo. Ringo will mind his own business and out of nowhere, Milo would pounce on him and playfully bite him or slap him in the face. He will follow Ringo around the house and swipe at his feet or push him with his body. Even as I type this, Ringo is walking around the bedroom while Milo sits in the cat tree eyeballing Ringo waiting for him to leave the room so he can follow. He will chase Ringo around the house until Ringo finds a high spot that Milo cant reach. From there, Milo will meow and howl for what seems like forever and I am guessing its out of frustration that he cant reach Ringo.
We have tried just about everything we can think of. Feliway diffusers (what the vet recommended), calming treats and collars, playing with him more to burn off his energy, and the only form of discipline that Milo reacts to is a spray bottle with water. If he sees us grab it, he will stop what he is doing and literally seconds later, he will go back to attacking Ringo as if he forgot that we just had the water bottle.
My husband and I have discussed that we don't want to rehome him. He is a sweet and affectionate cat, but we don't want him terrorizing Ringo constantly. Please any help would be much appreciated.