Watch him become the vilain as they finally find a solution to the reactor problem and he realizes that what was making him so happy lately was not just the thought of an unavoidable apocalypse, but the idea that they were all going to die together.Jasper should have been speared and killed instead of surviving.
Seeing Clarke end him will be traumatic to her, but so good for us.
If The 100 is good at something, it's at turning sympathetic characters into hated ones we watch die with glee