Cat Suddenly Aggressive????

I've had Frances since he was 4 weeks old. When he was 1 1/2, I got a new cat about the same age as him (although much smaller in size), Joseph. I kept them separate for 3 - 4 weeks before integrating them. That wasn't too much trouble. Joseph was sweet but definitely the 'alpha male.'

It's been 4 or 5 months. No issues. Out of nowhere, Frances has started stalking up to Joseph when he's asleep on the floor and biting him on the back, trying to incite him to fight. Joseph is very laid back and just walks away. Frances chases him, bites him, and uses his size to plow him over.

This isn't ALL the time, sometimes they play nicely together and sometimes sleep together on the same bed...but it DOES happen, at least once per day. I'm worried because I'm gone all day and not there to break up the fights. I don't want Joseph to get hurt, Frances is SO much bigger than him. Well, Joseph was an alley cat before I adopted him and can probably take care of himself...I just don't want ANYONE to get hurt.

Advice??

This must be really tough for you, Julia, to see your boys being rough like this. Are Frances and Joseph neutered?

Yes, they're both neutered. They are both adorable.

Bet they most certainly are, Julia, such precious boys you have! Would it help if each day you made a routine of special playtime with Frances when you could share some nice fun interactive play! You could try wand toys, toys for him to chase, roll around on/in, etc, and really get out some of his kitty energy! This could be fun for the three of you if Joseph decides we want to join in the game, as well. If you observe Frances getting a little rough with his brother, do your best to divert his attention perhaps with a Cat Dancer, or some other fun, eye catching toy. Hope this helps a bit, other Behavior experts will be along shortly. Play nice, now, boys!