Devon wasn't the only person who had the devil bloodline flowing through his body, Zaylee also had that same blood flowing through hers. But, unlike Devon who didn't have access to his powers back, she had a brief of her power given to her just like the others.
Her own fallout was that while she had her powers back, she wasn't capable of using them without facing a setback. The setback was, that once she unleashed the power inside her, her devil's form would emerge instantly.
Truthfully, there really wasn't any much difference between her and Devon. Devon was left with a tiny portion of his, while she had the strength, but wasn't able to really employ it.
Zaylee would have preferred to keep the matter of being a member of the primordial devil race a secret, but the instant she felt Devon's life was on the line, she knew there wasn't any other choice other than revealing that side of her.
