Results: Do you have 2 pets that for the life of them just can't figure out how to get along at all?

I have these 2 fixed male cats 1 who isn't quite 2 years old and the other 1 who is somewhere between 13 to 15 years of age which I some how went from cat sitting to the cat full on claiming me his owner no if ands or buts lol and since the first day this old cranky cat arrived him n the young one are always at it. Usually younger one purposely doing something to piss the old one off but luckily he isn't a scraper moreless extremely verbal with hissing and growls