Sounds like you have two male cats. If they are not nuetered, do that ASAP. Also, are there any stray males lurking around your house now? I had a cat for 7 years and this group of strays showed up with a big Tom. My cat started spraying all over the house and acting a lot different. Things calmed down when the stray family was gone. Also, I had to learn the hard way to recognize the dominant cat in the house. I always fed Spike first, picked him up first, greeted him first. THen he stopped "marking" on my clothes and shoes. One more suggestion: you may want to take your cat to a vet to check him out. Maybe he has something wrong that is causing him to be a meaner. Believe it or not, they put cats on anti-depressants and anti-anxiety medication just like humans. My vet told me has 20 cats on "kitty Prozac."
Good luck! Sherry