Loki agere fic concept
Coffeeshop modern AU where Sylvie is a regular with her little one (Mobius) and Loki is just very taken with them. When he's on a break one day, Loki decides to ask Sylvie about maybe setting up a play date? Loki is still very new to taking care of Thor, who tends to have some temper issues because of (divorce? Parental death? Something), and is having a very hard time adjusting to living a small apartment with his biologically younger, adopted brother taking care of him.
Mobius and Thor seem to really hit it off and their caregivers become closer too, taking on babysitting jobs for one another, talking about local daycares, etc.
If you like Sylki there's room for a romantic plot line, or they could stay friends. I think the idea of Sylvie being a #girlboss and Loki becoming a househusband against his will is really funny, especially if they're just friends/neighbors/roommates. But maybe Sylvie finds a girlfriend (B-15?).
Maybe Mobius is this big comfort blanket who helps Thor calm down during the tantrums not even Loki can fix.
Maybe when Loki and Sylvie fight it freaks them out, scares them beyond reason and needs to be fixed.