Tate was born in 30some years ago, yet he remains and immortal teenager. No, he's not a vampire like a certain blue eyed girl, but instead a ghost.
Hugo and Constance Langdon had Tate in 1977. Tate was the brother of Adelaide, and Beauregard. He's the only one out of the three not burdened by some sort of mental or physical defect, although he is psychologically disturbed. This is due largely to his father's absence and his mother's neglect as a child.
Tate's homelife as a child wasn't pleasant. Constance left Tate's father after having an affair with the neighbour, Larry. As well as having that weight on him, the 7 year old blonde had to deal with being ridiculed at school for having a sister with Down Syndrome, and persistent verbal abuse from his mother.
At 16, Tate's brother was murdered by Larry. Shortly after Larry moved in to try to play the part of a father in Tate and Addie's lives, Constance had enlisted him to kill Beauregard since she couldn't live with the shame and humiliation. Larry and Constance are unaware that Tate knew what really happened to his brother.
A year after the death of Beau, in 1994, something in Tate snapped. He did large amounts of cocaine before heading out. Before going to school, he went to Larry's work and set him on fire as revenge for what Larry did to Beau. Then he headed to Westfield High to commit a mass homicide, killing 15 students and sending an unknown number to the hospital.
He then goes back home, satisfied with himself. Only minutes before his life is ended, does he realize the truth of what he's done. But Tate figures there's no turning back now. What's done is done.
The SWAT team managed to track down the shooter and storm up to his bedroom, ignoring Constance's cries for mercy. The door to Tate's room slams open and Tate is sitting on the bed, waiting, smirk on his face. Realization has come and gone, and he just stopped caring all together of what was to happen.
The SWAT team trains their scopes on him, and he mimes putting a gun to his head..... Before diving for a real gun hiding under the pillow. Before Tate has a chance, the SWAT team shoots him 17 times, killing him in an instant. His spirit, as well as many others, resides in the house.
Once Josh, Andy, Jordan and Annabeth move in, only then do they find out the gruesome and macabre history of the house.
Unfazed, they chose to stay. Once and a while, the ghosts will come out to interact with the family and guests. Tate comes around most often though, finding solace and friendship in Jordan. As well as Jordan, the blonde boy has managed to find himself someone who cares for him and accepts him for who he is and what he has done.