Ruffled Hair

Will Solas is an ordinary kid. Or so he thinks...
When his class goes on a field trip to St.Peter's bascilica, something happens to him, allowing him to open Rifts in the sky, and making demons appear, also granting him the ability to walk through a Rift so that he can travel to far away places. What is the meaning of this? And what made him able to do this?