I would get rid of the guilty party. They are so cheap at that size, I would never keep one that is damaging they eyes because they dont grow back. If you are in a legal state, just take him back to where you got him and get a different one.
I agree with Jeff: I would also return the bad seed to the lfs!
I don't know if some p's are just born evil (ie. have an evil character), or that they might change when ageing, but I wouldn't risk the eyes (and lives) of your other reds, and trade him in for a more sociable one.
when I first bought baby reds I got three. Well two of them worked as a tag team and killed the less active baby p. but I didn't know it due to being at school. Well that weekend I bought a new baby to replace dead one and those two asses eventually killed that one too. somtimes they are like that
well the one guilty p killed the others last night so now all i have is just that one in the tank and the fish store i got them from wont take them back so im just gonna keep the guilty one soon hell be big enough to put in my big tank with the others probly in like 4 months so ill just keep him thnx 4 the help