Eboue
nasty little twerp with crazy bitter-man opinions
She's showed signs of instability and insecurity but so have plenty of characters. She goes from someone we're meant to be at least partially rooting for to the point of literal insanity within a scene, all because her mate died. This being a character who's spent her entire existence being persecuted and with people who wanted to kill her. Getting brutal and holding no prisoners would've been fine - becoming the show's most evil character within the space of an episode is just shite writing. And I say that as someone who liked the idea of an extended arc where she started to go a bit mental. It was done terribly.
missandei getting decapitated right in front of here caused her to snap