I'll leave reliable treatment advice to lilspaz, but my instinct says leave it be. If you could post a pic of it that would help us determine how bad it is. In general though, rats heal fast and putting neosporin could cause it to heal outside in, trapping any bacteria and setting him up for an abscess. Best to let them heal inside out.
There still sounds like several things going on. Introing males are always tricky, and some rats just don't like each other. Add to that females and young males hitting their hormonal stage. The easiset intro age is 6-12 weeks old. Before that, they can be mistaken for prey by adult males, and after that hormones start kicking in.
What intro process have you done with the boys so far? Improper or too rushed intros can result in excessive aggression and fights. It may also be just that, bullying. Sometimes a bigger male will pick on a smaller male.
What exactly is happening between Hector and Robin. Does Hector go up and get in Robin's face, cornering him and provoking a defensive bite for example? Or does Robin chase Hector around and attack him. From what little I know, the fact that it's a face bite, sounds more defensive on Robin's part. An aggressive attacking rat will go for the haunches and back legs.
What other kind of behavior is going on? Boxing? Stand offs? Sidling? Poofy fur? Rat ball fights? Slinking and stalking?
The first thing I would do, if it were me, is to either spay all of your females or all of your males at the earliest opportunity. Your babies are wiley and clever, and you will be playing with fire not to get one of the sexes fixed. All it takes is one mistake or one determined rat. For all my care, I've had two rat escapes with my boys in 2 years. If I'd had mixed sexes, I'd have 30 or more rats instead of 6 right now.
Not to mention intact males and females in one space raise the aggression and stress level in all your babies from all the hormones percolating.
Neutering the boys will have the benefit of cutting down on any aggression. Spaying the females will prevent pregnancy and 99 percent of mammary tumors. After that, you'll be able to house them all together, or have more options on house mates. Often an aggressive male can't be housed with males, but will fall in love with a harem of altered females.
Do a little shopping around for a spay/neuter vet. I've got two in my town who are excellent with rats. One charges 35 for a neuter, and the other charges 90 for a neuter.
