One of the most enjoyable aspects of following a TV series is watching how characters change and develop throughout, although some characters have much more drastic arcs than others. Whether through an internal transformation that sees them question the very nature of their selfhood or exterior factors that cause them to reconsider the foundations of their identity, watching characters learn and grow adds depth to a series narrative. While certain genres, like classic sitcoms, are defined by characters resetting at the beginning of each episode, others have their cast members change drastically throughout the series run.

https://screenrant.com/incredibly-drastic-character-arcs-tv-shows-list/