Ren isn't his surname. He is a member of the "Knights of Ren".
I'm aware. I just used Ren off the cuff... same was as I might use Kylo.
Anyways, I'm looking forward to finding out what his REAL name is. Part of me thinks that by the way he talks to Vader's helmet that his name is really Anakin Solo. Again, borrowing from the books but still viable.
Also, there's an article on the net that says that Rey was abandoned on Jakku by her parents when she was a baby. The character played by Max Von Sydow is rumored to be a former Imperial Admiral whose fleet was abandoned and forgotten by the Empire after the Battle of Jakku and the surviving crew make up the population of the settlement where Rey lives. Consequently they all despise the Empire for abandoning them
I think that there might be a plot point where the settlement is secretly being looked after by the Rebels/Resistance/New Republic so The Vicar (as MVS's character has been referred to) can keep an eye on Rey (who I also suspect may end up being Kira Solo) and keep her out of danger. What they don't count on is Luke's lighsaber landing on Jakku and all hell breaking lose.
The closer to the time of release and the more info that is released the more theories I develop.