The episode’s writer Elisabeth R. Finch wasn’t so willing to part with Catherine, and instead presented Thatcher as another option to remind viewers meaningful characters aren’t immortal.
As Krista Vernoff stated, Grey’s Anatomy had a streak of characters going through really bad situations, but then pulling through and surviving their tough times.
Catherine seemed like an easy candidate to break that streak, as Vernoff told TVLine the procedure the character had is one “few people survive.”