1. The Portal Opens

In the future a portal opens which no one can enter till someone falls into the portal so the exceeds go in after him. When Natsu try's going in the portal the portal wouldn't let him in. ignoring everyone's warning some of the guild members kids go in. why does the portal only open for children and exceeds? and is going to the past going to change the future? ( this is the first fanfic of the series i'll be making) { NaLu, GrUvia, JeRza, GaLe, RoWen, MiraXus.} [ book 1]
The second book is called Fairy tail: A portal of the present time.