I could offer some help!
Since they are all males cats, I think its a territorial thing, male cats are known to be more aggressive towards male cats if they think the other male is trying to size him up.
But if this is not the case, with the territorial thing, maybe he wants to play but gets...
Hey! My cat does this some times, the whites of your cat's eyes is bound to show at some point, but if the discharge is coming out of the white protective eyelid I advise you see a vet.