One of the things Game of Thrones gained attention for during its initial run was its approach to character death. While a lot of shows would claim complexity by killing off a nobody from time to time, HBO's excellent fantasy series let huge names drop with alarming frequency. Everyone remembers the first time they saw Ned Stark on the chopping block or Joffrey Baratheon succumbing to poison. Tyrion Lannister scored one of the most satisfying kills of the series when he put down Tywin, but what pushed him to pull the trigger?