dominance

Almost a year ago I neutered one of my male rats, but all my other rats keep annoying him, sniffing and touching his genitals. And they all also hump him, I just feel bad for him, I don't know what I can do. I don't really want to neuter the rest of them, because that cost alot of money :(...

Just for some background: So I adopted 4 sister rats from a rescue shelter. Saya, Maia, Yuki, and Ava. They’re roughly 8 months old now. Everything was wonderful, they all got along. Unfortunately we had a situation a couple months back where somehow 2 wild rats had gotten into the house, and...