User blog comment:Tierhalibelbrylle/RWBY X Red vs Blue/@comment-4197234-20140529033743/@comment-3146930-20140529204217

Well RWBY could take place on another planet in our galaxy in the future, thus allowing the characters of RvB to visit that planet and do a crossover with RWBY. I mean I still think the idea of a crossover is dumb, but there is some wiggle-room to at least allow the possibility of it.

Just as a bit of fun speculation, Halo 4 reveals that humans used to travel all over the galaxy before the war with the Flood and Forerunners, so if these humans had a colony just out of reach or protected from the Halo Array, they could have evolved. Eventually, they gained abilities thanks to the planet's own special properties (Dust), allowing them to gain the use of Aura and the ability to use Semblance over generations. Unfortunately, the firing of the Halos destroyed any advanced technology they once had and over time they were forgotten, leading to the world of RWBY we know now.