Underworld Academy or Life as a Familiar

The MCs in one my novel both attend a school in the outer ring of Hell, called Lucifer's Academy for the Unholy. One of the MCs is dead, and she's in Hell because she, as a misincarnation, is considered an unholy being and is not allowed within the gates of heaven. The other MC is a summoner, and Prince Bully Magnet.

The Misincarnation, because she's not alive, is incorporeal in the mortal realm. At some point the Summoner agrees to help her become physical in the mortal realm on one condition; He summons her as his Familiar. So in the mortal world, she is a salamander (The form of her soul), but in the underworld, she is herself.

The story goes back and forth between mortal and demon realms, both at and out of the academy, but I can't decide if I should focus more or less on the Familiar part or the Underworld School part

 

Best advice I can give is to start writing and see what happens, see what you find more interesting to write and focus on before you pick a solid route. You'll probably find that the further along you get, the more fleshed-out your plan will be.

One thing I would ask is how are you switching between these places? If the academy scenes are flashbacks, take them slow and see what develops and how it mirrors the "main" plot in the mortal realm. If your characters go backwards and forwards between realms then make sure it's plot-driven and makes sense, and the focus will come.

 

They get into and out of hell through pentagrams. In hell is primarily focused on the girl, while the mortal realm is focused on the guy

 

Then I'd say see what your plotline requires and where that takes them, if you're jumping between through these pentagrams a lot then the reader is going to get bored of the back-and-forth, so it's definitely best to have a stronger focus on one or the other. Personally, I love the idea of a school or academy in Hell, but I know a lot of people would rather see the Pullman-esque familiar thing. What you've essentially got are two plots (or concepts, at least) that are worth exploring, whether together or separately.