Aggressive rat :(

Let’s start off at the beginning, I took three male rats (Sebastian, Julian and Caesar) from a friend who could no longer look after them and only a couple months after having them, Caesar had to be put down due to neurological problems which was extremely heartbreaking. After that incident, Julian has gotten extremely violent and aggressive towards Sebastian and I have no idea what to do. Julian pulls chunks off fur from Sebastian’s skin and leaves big scabs all over him, he hoards all the food and doesn’t let Sebastian eat and I’ve resulted in housing them separately because no matter what I do, nothing improves and it just gets worse. Sebastian has gotten extremely skinny and I can feel all of his bones and I’m so terrified that I’m gonna have to put him down as well so if there’s anything anyone knows, please let me know! This is very heartbreaking and I have no clue what to do.