Malcom is a special inspector sent to Headquarters by the Order's administration at the Vatican after General Cross and the other Exorcists return with the Ark. He is a tall man who speaks to intimidate those around him. Malcom is quite critical of General Cross and seems to know much more about the Ark and General Cross than he lets on. Currently he wants Allen tried for heresy as he sees his possible link with the 14th Noah as a liability. He has ordered General Cross to a desk job and has forbidden him from speaking with Allen. He wishes to use the Ark to attack the Earl and is setting in motion plans to find new Exorcists to bolster the Order's power for the coming final battle. Most recently he has decided to forcibly invoke Lenalee's Innocence, guilting her with Komui's joining the Black Order for her sake, despite the fact that it could be disastrous both for the Black Order and Lenalee's life.

He appears in Lenalee's flashbacks to her early time in the order when she sees him. He apparently had something to do with her early days of imprisonment with the Order. Even now when he's around Lenalee becomes stressed and goes to Kanda to calm down the way she did since they were kids. Rouvelier has a toothbrush mustache and is said to make great cakes.

(Source: Wikipedia)