This is the episode I’ve been dreading. It’s the reason that I haven’t re-watched the series since it first aired.
Immortality is a quality of gods and monsters. Zeus, Odin, and the monotheistic God are all immortal, but so are vampires, zombies, and the devil (Voldemort did try his damnedest, though). It is then unsurprising that a tension between moral and immoral immortality would appear in works that feature the possibility of living forever.