I agree with you. It looks like he got jumped from behind. He'll know now.
I use betadine gel on comb, ear and wattle wounds. Surprisingly these areas don't seem to get infected easily. On the down side they bleed a lot and it looks much worse then it is. I've had a couple with eye damage and that's very worrying.
Poor old Fabio.

Meat treats are in order and if you have some a couple of days of a vitamin supplement.
If Fabio had lost to the point that he would run then you would have major problems. The hens I doubt have much interest in Captain given he doesn't even have a proper pair of spurs yet. Hens get to trust their roosters I've found and a sudden change in senior rooster really upsets them, especially if it's some underage upstart!