I'm going to share one of my favorite WoW memories and then go to bed.
I was playing my nelf shadow priest and my friend and I were messing with some low level blood elves. I would use a dot spell on one of the elves, then mind control them and use a healing spell, which would stop the dot spell from killing them. Basically I just kept them close to death and prevented them from running away with mind control. This went on for maybe five minutes, not very long. Afterward I felt kinda shitty for doing that. I'm usually a horde player, but my friend and I migrated to alliance when we joined a new server.
Anyway, my friend went to bed and I decided to do something good to balance out my karma. So I rode to the tauren starting zone, cuz I fucking love taurens and remembered the early quests really well, and found a new player, like level 5. The way xp worked was that if you weren't in the other player's party, whoever did damage first would get all the xp when the mob died. So I started following this new player around, planting my dot attack on mobs the tauren player had shot with his bow. I followed him around doing this for hours, helping him get xp and protecting him from the more dangerous mobs.
I was alliance. He was horde. We could not communicate through chat, as the game imposed a language barrier. But he understood that I was helping him. It didn't take long to gain his trust. We ran all over the starting zone all night and I helped him do his quests. He seemed really happy for the assistance. Eventually some higher level horde player showed up and chased me off, but I felt like I'd done a good thing. Whoever that level 5 tauren was I hope he looks back on that memory just as fondly as I do.