Okay, I kinda take back what I wrote here. I just watched Episode 4x04.
I think it’s safe to assume that Raven’s tribe is to blame for the damaged village in 4x02. That leads to the conclusion that Raven’s tribe is to blame for whatever happened to Nora and Ren. Who would have expected that? I sure as hell didn’t.
I think what Raven says in 4x04 is a really good hint:
The weak die, the strong live. Those are the rules.
That might be the worldview Qrow talked about earlier, the one he doesn’t agree with. It makes sense as he left the tribe and doesn’t think too highly of it. So… what if her tribe follows some cruel Darwin-misconception of ‘if you don’t make it you’re not worth it’?
Maybe that’s why Raven saved Yang only once. That’s her rule. Because if Yang can’t make it on her own she’s not supposed to make it. If she’s not strong enough to make it she’s weak and she dies. Raven allowed herself to save Yang once, but only once. It’s dark. It’s cruel. But it would make sense.
Raven told Qrow to tell Yang not to expect any further kindness and maybe it’s not that Raven doesn’t like Yang enough to be kind to her, maybe Raven just doesn’t believe in kindness. It’s not about which feelings Raven might have for Yang and not even about Yang at all. It’s about how Raven sees the world and saving someone, even her daughter, more than once is against what she believes in.
Maybe Raven sees things. She definately knows things. Qrow said he knew that Raven knew about Yang’s arm. So maybe Raven made up those rules because eventually she has to decide where to intervent and where not. Maybe those rules are just what she believes in and she wouldn’t break them for anyone, not even her daughter. Maybe that’s why she gave her daughter away.
So what happened to Ren and Nora? I think we can only guess but in my mind their backstory is getting darker and darker. Maybe Raven’s tribe is just a pack of robbers who believe that if you can’t protect yourself it’s their right to claim everything you own. Maybe they robbed Nora’s and Ren’s village and killed everyone, maybe Grimm came and killed everyone. Maybe it’s much darker and Raven’s tribe decided who’s to live and who’s to die. I just hope we’ll find out soon.