Miraculous fans only! (or else you won't understand this question) Is Felix Graham De'vanily yes, the kid have 290IQ, a sentimonster? Consider to episode 'Gabriel Agreste' as known as season 4 episode 9 Gabriel once said:
"All I need is a snap of my fingers to make you disappear from this place"
Felix: "You wouldn't dare"
Gabriel: "Are you willing to take that risk? Think of your dear mother"

this conversation is after Felix say out his suspicions to Gabriel that he is Shadowmoth. She I think we have short of evidence that he is a sentimonster, and object of amok might in the one of the Graham twin rings some says they are lost miraculous. Also Graham family is Emilie and Amelie's birth family before they have their own, Emilie married to Agreste and Amelie married to De'vanily