Fantomex is a X-Man that has really grown on me the last few years in Uncanny X-Force. What I like about him is the fact that he really doesn’t belong, yet somehow sticks around the X-Men. He was my favorite part of the Grant Morrison era due to the fact that him being so unique.
The character is a hybrid human/mutant/sentinel that was created by Weapon Plus program to hunt down mutants, but eventually becomes sentient and has allies himself with the X-Men. And thanks to his programming, he thinks that he’s French.
He is a mercenary by trade, and that is how he got caught up in with Wolverine and Archangel’s secret X-Force team. He reminds me a lot of Deadpool, but without the annoying parts and a more practical conscience. He gets under everyone’s skin and is constantly manipulating people. And that’s what makes an interesting character.