Well the current popular theory about Raki is
that he's dragging Priscilla along with him to find Clare because he's hoping Clare can help Priscilla out before she reaches her limits. Raki, after all, has seen Clare awaken and then come back, twice. So he probably thinks that Clare can teach Priscilla the same thing. Unfortunately, Raki has no idea of the history between Clare and Priscilla, so I see Raki being disappointed in the end.