User blog comment:Seieireppa/God Eater:Universitas, chapter 28: Beoblade's Resolve, part 1/@comment-14812118-20150711203553/@comment-1419424-20150711203953

I mean it's sort of the same way Sigma and Feldman found themselves there. It just... sort of happened.

Of course, it's never COMPLETELY random. Here, it was also partly because the Horizon found Beo worthy and decided to pull him in so he could prove himself. In Sigma's case, his determination to undo the root cause of Aragami called out to the Horizon, and in the case of Feldman, his desire to basically dominate the world attracted the Horizon's attention.

What I'm trying to say is that the actual method by which one arrives at the Horizon is completely random, but WHY they arrive there isn't.