Michel was a Hollow created by the Unnamed Female Arrancar for her plot to destroy Karakura Town.
Before revealing his true motives, Michel put up an act of being very friendly and kind. He would always smile and be happy to help anyone. He broke away from a group of people wanting his autograph to ask Kon if he was okay after their encounter with a Hollow. He cared for the people of Karakura Town and mentioned how great it was they had the Karakura-Raizer Team.
In truth however, he was just manipulative. Using his hypnosis, he sought to bring down Karakura Town. He told the Karakura-Raizer Team that he was giving them special flying capes but in reality they absorbed reiatsu, weakening them so he could more easily deal with them.
(Source: Bleach Wiki)
