Suspect it's more Metatron knows Ashley doesn't really mean anything malicious with the pranks and tolerates them!
Here's my take of each of the "core group", with does not include Aspasia (she's like an intellectual) and Maya (haven't interacted enough to know, really) or beyond
MC: Takes it one day at a time, a snark, and feels like he's the parent a fair amount because of who's around him
Sam(antha): Has less subtlety than a bull in a china shop. Plows ahead without regards to danger or self-preservation. MC clearly likes her/him but is also annoyed with the "just moving ahead" strategy. Doesn't care much for Celica.
Celica: Acerbic, mouthy (wordy?), dislikes Sam, but a good companion IF you can get over her mouth. Probably the most intelligent of the original group, except maybe Metatron.
Metatron: Team Mom, rather scary until her emotions open up but still a good ally. Once she is more in tune with emotions it's easy to see how much she cares, from helping Sarah understand her Aether side and putting up with Ashley's constant pranking (still waiting for the prank war to start though!)
Sarah: personal favorite. Shy, very unsure about herself, but has flashes of brilliance. Best friends with Ashley and clearly cares for her. Exploring Sarah's emotions helps her feel more complete.
Ashley: Talks incredibly big (Demon Queen/Succubus goddess) but it seems to be more coping mechanism for something. Snarks quite a bit, doesn't have much self-preservation, but helpful and a good ally.
So...how close am I to how you envisioned them?