My boyfriend and I moved in together a year ago, each bringing one cat. The older cat moved with me on moving day and the younger one arrived a few days later.
One cat is an eight-year-old female. She's pretty calm and quiet, doesn't like playing so much, and doesn't even climb up the furniture or the tables. The other cat is a three-year-old male; he likes to play aggressively (biting, scratching, hunting) and is very loud. We may have presented the cats to each other poorly, as it seems that they simply hate each other. Both cats are neutered.
The problem is that the younger cat likes to hunt the older one and corner her. He sometimes slaps her when she's walking near him. When she's cornered, she starts to hiss and growl. Frequently, this "game" becomes dangerous if I do not stop them. When I come back home from work, I often see scratches on the noses or eyelids of both cats. They fight this way several times a day.
We've already tried Feliway (more than once), spray water, and confinement. Nothing works. It's been a year since this started, and the behavior is the same. I read "How to get cats to coexist in peace?", and tried the suggestions. When I leave home in the morning, I move each cat to a separate room, with a door separating them. We've been doing this for two months, and still no success: when we leave them free with minor supervision, they eventually start "playing" again.
They have a lot of toys in the house. They have cardboard castles with holes, and I play with them every day, with toys (including a kinder surprise inside egg); we try to give them variety.
I do not know if the younger cat is acting aggressively due to jealousy, a mean streak, or is just simply being playful. I'm scared because of the scratches, and I fear that any day one of the cats will lose an eye or worse.
How can we handle this situation?