He has 666 stickers on the bottom of his shoes, a fallen angel sign can be seen on the street near his house, and he owns multiple copies of ' Faust', which is a book about a man who sold his soul to the devil for infinite riches and pleasure. There are clues that point out that the Neighbor may have had an affiliation with the devil.
The game ends with the player being buried alive, ending his life. We can get an idea that the Neighbor used to have a family, as seen in Alpha 1 with the children room. He is taken to the Neighbor's house, and realizes that his Neighbor is hiding something in his basement. The player's car gets hit by a utility pole, sending him into a coma. 4 Alpha 4 - Beta 3 (Like Father Like Son).