In Fullmetal Alchemist there are a bunch of amazing well characterised characters but one of the most interesting characters is Solf J. Kimblee the Crimson Lotus Alchemist whose power lies in creating imbalances in objects to create powerful explosions. An amoral psychopath who despite being nihilistic he thrives on living on the edge and the pleasure he gets from sound of explosions and suffering in general. But despite being crazy he is surprisingly the most sane man in the room as he is an intelligent philosopher who knows of the inherent brutal nature of humanity and the world and has no tolerance for anyone being inconsistent with their philosophies and in fact he is the character who is most consistent his own brand of views in life which he is aware differs from societies' standards nevertheless he argues his points well enough to hide any heresy on his part. As he is the very personification of the aforementioned brutality himself he understands it and uses it well to argue his points exposing the hypocrisy and inherent impracticality of the morals behind any of the main characters of Fullmetal Alchemist including the villain faction which he sides with despite having no stakes in the conflict and simply wishes to see which side would emerge victorious. In fact his role in driving the plot is minimal but at best Kimblee is a tool for balancing the narrative and laying the flaws of both hero and villain bare before the audience. Can you imagine what would happen if he was a X-Men villain wouldn't it be great to see him tear apart Xavier's dream of peaceful cooperation and to hear him laugh in his face when he uncovers that Xavier is actually the most inconsistent with his own brand of philosophy. Or how about when Cyclops goes over the edge? Or maybe the Purifier's own desire to kill mutants while at the same time they are willing to use them as weapons in their war and have him berate them for heresy? Or in fight Logan might be out matched as he has to deal with a man who can explode things with a touch. What do you think would Kimblee make a great X-Men villain?
In fact to get great break down I'll deliver a link so everyone can get an even better idea of him: https://www.youtube.com/watch?v=E8MxjtRe2sA