Because given the right circumstances even the hyperactive dragon slayer can become an innocent victim to the "dangerous" disease. Rated for minor swearing (NaLu).
Fairy Tail - Rated: T - English - Romance/Humor - Chapters: 25 - Words: 84,054 - Reviews: 191 - Favs: 208 - Follows: 183 - Updated: 6/28/2015 - Published: 3/6/2015 - [Natsu D., Lucy H.] - Complete