Julien is a member of the Assassins Guild and is a Science-Based Mutate. After his sister Bella Donna got married to Gambit he challenged him to a duel. He lost and Gambit was banished. Julien was killed by his father Marius after he went mad and took over the Guild to aquire the Elixir of Life.
Juien Boudreaux possessed enhanced strength, speed, quick reflexes, and razor edged talons. The elixir of life maintains his body.
Julien only appears in one of the comic book adaptions; X-men Evolution ( season 4 episode 6 titled
). Here he is a member of The Rippers (this version of The Assasins Guild.). His rivals are those from The Thieves Guild. He also seems to hold a gruge against Gambit even Bella Donna does not exist. Other than that not much else is known about him .