Hmm. Who he is in FTL remains a mystery, obviously. (I say he might be connected to Rumple, but is against him?)
I believe that he is here to protect the book. That he ultimately is working on the good side. Knowing now that he has the ability to fix the book, maybe he has created a back up? I feel that the book will be destroyed, for good, by the season’s end. So when he had the book, he created a duplicate. I’m not sure if that will effect things in using a duplicate though.