I have been reading non stop to try and find any who has heard of this but I am not really getting anywhere. I have found articles on old rats beating up on the smaller ones...but my newest 5 week old is constantly jumpin all over my older rat who is twice his size. Wally my older one does not seem so even care and I dont know if its just that Riley my younger one is trying to play but it doesnt seem like it. I am new to this so I may be over reacting. Wally seems to get his food and then Riley comes tumbling down and fights him for it even if he doesnt want to eat it. Then I hear Riley squeeking at night because Wally is trying to push him away from him. I tried watching the two but it just seems like Riley wants to play but I dont know for sure. Riley pounces on him and sometimes will grab Wally's paw and bite it. It was so weird. But that only happened when the two were uptop waiting for me to give them treats. Help! Someone who would know anything about this!