Not just that Julia can do magic, but she transfers some of her capabilities to the people she gives blood to.
And we're not talking about the resistance to sunlight only.
She's also untraceable, especially to location spells. And some sort of camouflage happens when crossing magical barriers.
This kind of thing happened to her brother or me, and both of us have had her blood. All the tiny discrepancies around my girl make some sense now.
My change was also similar to what she described. I didn't notice anything but, at some point, I was capable of crossing Amadeus's barrier without alerting him. That's why the door was closed when we ran towards Fortress under attack.
No one knew we were out.
Also, my physical strength increased without alerting me. One day, I could jump farther without much effort. And I was also faster, stronger, more sensitive, and so on...
