I'm sure you saw this David Kamp quote from the Reddit Q&A: "Adam is very good not only about not revealing spoilers, but also being private and circumspect about his actorly motivations. He told me that there's something within him, personally, that he calls upon to portray Kylo Ren, but that he'd prefer to keep that something private. Extraordinary actor." I'm not at all surprised by this, based on what Adam has said in the past, but damn, that's sad.
It is very sad but it’s also a very dignified comment that makes me respect Adam even more. I think his performance in TFA made it clear that he was drawing on something from deep within himself, so I’m not surprised that he has some kind of intensely personal touchstone for the character that he chooses to keep private.
That kind of comment also makes me more convinced of Kylo’s eventual redemption - Adam clearly identifies incredibly strongly with the character and his pain, and I don’t see him being interested in portraying a plunge into irreversible evil for a character who is, to a certain extent, an extension of his own self.