Warning up front!
Irregular updates: one chapter a month, maybe even less?
Everyone is out of character. The writing is at an elementary school level.
The heroine is Illyasviel, the protagonist of Prisma Illya. Her pairing is with Hermione. It should be a happy ending? It might get abandoned.
Gryffindor x Gryffindor. Cross-house romance is nerve-racking, so same-classmates is the way to go. Illyasviel has a pretty powerful golden finger (I haven't added anything new, so you can look up how strong the Servants in Fate are). In this setting, Prisma Illya's power level is higher than Harry Potter's. I may easily stop updating, so enter at your own risk.
I haven't seriously studied the details of the backgrounds of Prisma Illya or Harry Potter. I just happened to have this idea and started writing, so please don't nitpick the details.
I don't have an outline, but I've thought of a way to wrap up the ending, provided I don't abandon it before I get there.
Theme: Who doesn't want to be a lazy pigeon?