User blog comment:Zathronas/Analysis by an author-Hiatus Edition: Nora Valkyrie/@comment-24994749-20141122033505/@comment-24994749-20141123024558

Going by the theory that Ren and Nora (specially Ren) wanted to shadow the sheriff of the village outside of the kingdom because either :

a) they are from that village,

b) they are from some other outside-of-the-kingdom community,

My personal theory (going by the siblings in everything but blood idea) is that when they were young, they suffered great loss at the hands of the Grimm. Bonus points for the attack being detonated or worsened by negative emotion in town attracting them (something like what we saw in the WoR where the panic after an original small attack that had been controlled attracted further larger attacks). Ren's approach or lesson learned was to adopt that "zen" personality we always see him with. Nora instead, took the "live every moment as if it were the last".