My theory is Liz was born into an underground family, possibly royal, who was involved in spying for their country, code for “Berlin”. The symbol that is displayed on her scar on her hand, the wooden box that was found from Tom, and the envelope she opens at the bank vault as shown in the last episode is the family crest . I believe Tom is part of the same underground/family and placed in Liz's life by to protect her from Reddington. I believe Reddington is part of an interpol type organization and a double spy for whatever country will pay him. That is why he does not need passports or identity. He killed Liz's family in a house fire to protect his mission. In addition, his own family was killed because of his interpol operations, perhaps due to his double spying. That may also be why he killed Liz's family as blood revenge. Reddington must always spy on Liz to keep his mission going , so he set her up with her adopted father so he can always keep tabs on her. Liz's adopted father was also part of the organization. Reddington killed her adopted father in the hospital because he was going to tell Liz the truth. In the last scene she opens the envelope which I believe is a series of photos showing Reddington killing her family in the fire, and showing Liz as a child and the sole survivor. I believe Liz will now be faced with trying to obtain the truth from Reddington.