Teo was the result of an illicit affair between Arthur and a woman named Ana Sophia. Ana never told Arthur about their son as he was gone by the time Teo was born. Ana chose to keep Arthur out of Teo's life, and so Teo deeply resented him. At an unknown point, Teo was recruited by Arthur, albeit indirectly, into the CIA and sent undercover into the ALC terrorist cell. He eventually became the leader of the cell.
Meeting Annie, Auggie and Arthur Edit
In the Season Four premiere episode, titled Vamos, Annie was kidnapped by Teo. Annie had entered Columbia on an unauthorized mission sparked by her desire to clear Arthur's name after he was accused of manipulating funds. In the episode Dig For Fire, Arthur unofficially requested that Auggie look into Henry Wilcox, to find out if Wilcox knew Arthur was Teo's father, since Wilcox is rumored to have a drug connection in Columbia. The findings lead the two to enter Columbia as well. In the following episode, all three agents come in contact with Teo, who is revealed to Annie as Arthur's son.
Working together, Revelation of Paternity to Teo and "Death" Edit
In subsequent episodes, the three worked closely with Teo. Eventually, Arthur admits the truth to Annie: Teo is a double agent recruited by the CIA to infiltrate the ALC. Arthur also tells Teo that he is his father. In Rock A My Soul, Henry Wilcox, still placing blame on Arthur for the death of Jai, who was killed by an exploding car bomb meant for Annie during Hang On to Yourself, vows to kill Arthur's own son. Teo is then absent for several episodes, but pops up again in I've Been Waiting for You when Annie tracks him down.
He allegedly was killed in the episode Hang Wire:a gunshot to the thigh supposedly caused him to lose too much blood, before doctors got to him. However, his body was moved from the hospital, and his death was never outright confirmed on screen, leading many fans to believe Teo may still be alive. He has not been seen since the events of Hang Wire.