Well, I'm not a trainer, nor do I have any males but it sounds like they are going through the "getting to know you" phase. It's always a test when introducing a new fursibling to the bunch and it's up to you to ensure it goes smoothly. Make sure for right now, you separate them when you cannot supervise, until you're convinced they can co-habitat peacefully. If or when, a dominance contest ensues, you have to be sure to step in and let them know, you are the only dominant one, the Pack Leader... But understandably, Remy is just getting used to the idea of him not being the only one...Maybe start off by taking them both outside in the open environment for a lot of play time together...
I don't know if the neutering thing has a lot to do with it but if he just got neutered, you may want to make sure they stay separated until he heals.
Best of Luck!
Maybe someone else with males can come along and give you some advice.