Erementar Gerad, Toaru Majutsu no Index Recommendations
Index has a powerful secret, like Reverie from EG, and they look and act similar. The male protagonists both don't know why they're protecting her, and in parallel, an organization also want to protect her from someone who could exploit her power.
I really don't know but these seem so familiar. a guy meets a girl who gets caught up with the problems they bring along. both have action and will keep you watching.