Yeah, this whole Raynor storyline still isn't working for me. Apparently Rainer isn't the bad guy, there's some other guy/thing who is the bad guy and is also Bo's dad. As for why Rainer was erased from history, I think it was something to do with him rebelling against Trick while he was the Blood King. It might also relate to the prophecy about his return bring about Bo's dad's arrival. I'm not sure.
As for Trick and Evony, I don't think it was that he was "acting like a bad guy", it's just that the new threat, aka Bo's daddy, is such a big threat that they are willing to cooperate.
I've been a huge fan of the show from the beginning, but even I'm having trouble following this season's storyline. It really hasn't been a great season overall.
I do agree that Lauren turning Evony human was kind of random. Then there's the whole reveal with Massimo being her son, who was raised by Vex. WTF!