My cat was a biter. I had to train him to know it's not acceptable. When he bites I scold him and take him off my lap. The other day he was aggressive so I put him in the room his litter box is in and left him there for a while. When he came out I could tell he knew he was punished because his body posture (belly low to the ground). Then I went over and petted him.

His training has worked out really well because he used to bite alot but now he just has a lapse now and then and I have to remind him it's not allowed.

I think if you let your kitty know it's not OK to bite he will be more gentle with the other cat also.