YMMV / Arthas

• Moral Event Horizon: At what point you think Arthas crosses this is up to you but he definitely crosses it by the time he kills his father. Through it can be argued that he was posessed by Frostmourne, a more straight-up example is when he removes his heart and later banishes his own good side in a mental battle, leaving only evil within him.
• Tear Jerker: Arthas's horse Invincible's death, for those who have had a beloved pet die.