I know I did it in a comment somewhere but here's an official post about it.

The magic system in Main Character Syndrome is in it's infancy (and I only have 300 words to explain) but here's the quick rundown:

Magic is like strings. Spells are like a weave. People's souls have musical resonance that matches with the resonant strings of certain elements, creating elemental affinities. With me so far?

Most people aren't very aware of their resonant frequency, learning what their affinity is through testing or trial and error. A rare few are in tune with their own frequency, this allows them to use their own magic as strings without needing an affinity.

Being able to sense your own frequency like that allows you to shapeshift. Shifting is the safest use of this kind of soul magic, though things like blood and bone manipulation are possible (and incredibly painful if you're even slightly off).

Val is one of these people, though she's what's referred to as a 'partial shifter' due to her lacking the ability (or perhaps the willingness) to shift fully into an animal, instead choosing to only use parts to her own advantage.

Shifters actually led to the reverse of hybrids. When a shifter has a kid and they're still semi-shifted (such as with a tail or wings), the kid has a chance of inheriting that shifted part, as well as passing it down. Not all shifters have shifter kids so these parts that are inherited tend to stick around.