So, even though I'm fangirling over Chat Blanc, I eventually tried to move myself to the Felix episode. On Adiren' s Instagram, and I quote:
"Enjoying spending some time with these two! I wish I had a brother and sister- my cousin and I used to be really close, but I haven't seen him in the last year."
Adrien has already met Felix, or this cousin. This could mean the theory for Fleix being a Sentimonster is not true; but in Ladybug, we have seen you're able to make copies of different people.
However, I don't think Gabriel would allow Nathalie to traumatize his son like that. Gabirel still loves Adiren in his own way, and I don't he'd stoop that low; to make a copy of his cousin and think he's back.
Along with that, what are your theories for the Felix episode, and do you think he's a sentimonster or not?