Other forms: vendettas
A vendetta is blood feud, a quest for revenge. A vendetta might separate families for generations, with members of one family murdering those of the other, all to satisfy an ancient grudge.
If a friend of yours breaks into your locker and fills it with crumpled up newspaper, you will not be able to hold your head up until you have carried out a vendetta. Perhaps you can tie his shoes together during French class without his noticing?