[@Lady Athena]

Well Magic flows through a character, once they've unlocked the power of magic through a ritual (done in roleplay). This Magic will then form into some sort of source for the character to access, so they can start using the energy called magic. 

Some have a center point for their magic, Their magic taking some kind of shape and exists in a certain part of their body. Now they can use this magic from any point of their body, so it doesn't matter where it's at.

While others have the magic spread through the character's body like threads/veins/etc...

It's how the character's magic looks inside of them, the form it takes once it's settled inside her, that is the primary source of their magic.