One day, the three of them are walking along the beach and discover a magic lamp. They rub and rub, and sure enough, out pops a genie. The genie says, "Since I can only grant three wishes, you may each have one."
The elf says, "I've been stuck here for years. I miss my family, my husband, and my life. I just want to go home." POOF and off she goes! The elf gets her wish and she is returned to her family.
Then, the troll says, "I've been stuck here for years as well. I miss my family, my wife, and my life. I wish I could go home too." POOF! The troll gets his wish and he is returned to his family.
The orc starts crying uncontrollably. The genie asks, "My friend, what's the matter?"
The orc whimpers, "I am lonely. I wish my friends were still here." And that is why elves, trolls and orcs have remained enemies ever since.