In Cascade, why did Jade get Bec's powers? I know her sprite was prototyped with him but I thought that didn't matter. Like, why didn't davesprite merge with Dave when he ascended? Or am I missing something?

Jade got Bec’s powers because she prototyped her dream self in the kernel sprite and when you ascend using your Quest Bed your dream self becomes the godtier. Dave did not merge with Davesprite because it was a doomed Dave that was prototyped, not his dream self.