Board Thread:Character Discussion/@comment-6739926-20150118091358/@comment-4273152-20150126062045

If they have to make a canon reason, it may just be because airy magic is said to be incompatible with Dark Magic. We've never seen any Dark magic used on a fairy, and we've never seen fairy magic used on a dark magic user. Maybe they simply don't affect each other. Since most of the problems in the show are caused by dark magic, there's nothing Blue can do about them.