Yeah a lot of problems are caused by a boy interrupting another trying to mate with a girl. Just two roosters like this cause a lot more problems than say, 6 roosters that don't actively try to interrupt a mating.
Snape *might* turn out to be one of those roosters with low tolerance for other roosters in general. Some roosters just cannot tolerate any other rooster to the point of it it not being safe to have him confined with another rooster (coop/run), others are variably tolerant(can tolerate another being around, but cannot stand to see any rooster mounting a hen, etc), yet others are just fine with other roosters.
You know, I think Snape's attempt with Trinity (leading to the wound) came after Tank attempting with Trinity and being chased off, now that you mention it. Snape has been putting Tank in his place if Tank gets "ideas", but doesn't attack him outright (yet) - though Tank does have an occasional cut on his neck that is likely from Snape. They are otherwise friendly enough around each other - I'm hopeful that away form the girls, they'll be ok together for a little while. (They're not currently in the sight of the NN pullets now, because of where their new home is). But I'm going to rapidly get together contingency solo housing in case they start fighting - I've gotten a number of very nice very large (long) discarded pallets recently, and can use them like panels in a small enclosure with an attached run - and I have a few different areas I can give them their own "house with a yard" if they have to live solo.
Housing! It always seems to be about housing!!!!!!!
- Ant Farm