Grudges, or "How Far Do You Take It?"

There's this guy. And his tiny guild, Akatsukí. Five of them camped my brother mercilessly one day in Icecrown as he was soloing the group Argent daily. Later, my brother killed one of them in Wintergrasp because one-on-one (even two-on-one) he had infinitely superior gear and skill.

I've had a certain rule since I was a kid. Maybe less a "rule" and more an attitude -- you mess with my brother, you earn my eternal hatred and contempt. Forget the "protective big brother" role -- I was the rabid little sister. I would stop being friends with anyone who didn't like him, or thought he was "weird." My dad was my hero, but my brother was my role model. The most impressive thing my husband said when we first met was that he knew my brother and liked him.

So, about a month or two ago, the vile treacherous gankers of Akatsukí transferred to horde, and I saw one of these losers in my Wintergrasp today.

I decided not to heal him.

Someone else healed him. I debated asking them to stop but didn't think they'd be quite as sympathetic to my grudge as a guildmate or friend. I was rather miserable that he lived.

My revenge is pretty passive. I won't actively harm others, but I won't help them, either. Sometimes, with guys like this, I wish I were more vocal and crafty and mean, but the part of me that belongs on a PVE server just doesn't have the heart to retaliate properly.

So my question is, how long do you hold a grudge and how far will you go to seek revenge? What can prompt a grudge from you?