If Victoria & Riley killed Diego for knowing the truth about the sun, how'd Riley find out about Diego & bree's super secret ninja club? Did Diego tell riley to tell Bree he had a handshake as a last request?

Yeh, I think that was his last request because if Riley told Bree that he had the secret handshake sorted out then it might stop her from worrying about him because it makes it sound like he's coming back to show it her and not that he'd really be dead. I thought this was a really sad part of the book because it was giving her false hope that Diego was coming back.

Yeah, I think so. He was hoping that Bree would know he was dead. I also think Riley and Victoria tortured Diego to the point where he gave up some information.