Drew Avery

Bree's father was first shown in the series in a brief shot of his lower body in "The Tolstoy Principle (and Dad "talks" to Daniel)". In The Mistress, we hear his voice, and it is revealed that his full name is Drew Avery, the name that Nikki Bower gave him.

Background
He studied medicine at Oxford and has done research for several biotech companies, himself specializing in ribozymes. Though none of these companies has been mentioned by name, Daniel once found a box with a mysterious symbol that Bree recognized. This discovery led him to one of the company's warehouses, which he broke into and found a box of the medicine Bree's father had once been administering to her in preparation for the ceremony.

Bree's father met her mother while he was studying medicine at Oxford. They met by chance at a performance of the Tom Stoppard play "Rosencrantz & Guildenstern Are Dead" in London. She overheard his discussion with a friend and approached him to express her disagreement. He had been saying that the theme of the play was and Bree's mother stepped in to argue that the theme was actually Free will. As Bree put it, her father was "smitten like a kitten" after that.

Although Daniel was allowed to visit Bree, her father was nevertheless very protective of her. By Daniel's account, he would keep an eye on them while they watched movies in the "family room that's not like the nice family room." In contrast, he did allow Bree and Daniel to hang out in her room unsupervised and with the door closed. Daniel's relationship with Bree's father is complicated at its best, and downright uncomfortable at its worst moments. In one of the earlier videos, Bree's father pulled Daniel aside for a private talk. He asked Daniel to come to Bree's summer camp and film a play she participated in. Daniel initially refuses to go because it's a religious summer camp and Daniel thought that it "sucked" and was "so weird" to which Bree's father replied "Well, maybe we can't have you coming over anymore." Eventually Daniel decided to go anyway and showed up by surprise. He did not film the play though, his reason being that he was not going because of her dad, he was going for Bree.

Despite his strict and overprotective nature, Bree's father had a close relationship to her and in other respects seemed the softer of the two parents. He encouraged her studies in science and also enjoyed taking her out to watch mystery movies. He also had a role in her homeschooling, as evidenced by his mention of their conversations about Richard Feynman and Jared Diamond.

Bree's parents allow Daniel and Bree to go swimming and hiking. But when Bree asked to go to a party with Daniel, her father refused. After Bree sneaked out to the party anyway, her father caught her, grounded her and banned Daniel from the house. He was allowed back after Bree told them about the fake ceremony and how Daniel had kept watch over her. When Bree's parents tried to get Bree out of the ceremony and were met with resistance, she went over to Daniel's house and her parents actually encourage her to stay there overnight. Less than a week later, her parents were taken away by Lucy and a Deacon. When Daniel and Bree went back to the house and witnessed her parents being led away, they went inside and Bree found a note from her father hidden inside of P Monkey, but does not immediately say what it said. Much later, when Bree had been kidnapped by the HoO, Daniel went through Bree's things and found the note, and with the help of those on the forum, was able to crack the hidden code Bree's father had left for her. The hidden message led them to the site of the camp play, where they found a box containing a letter from Bree's dad and many important secrets about the Hymn of One, and revealing the reason why Bree was wanted for the Ceremony. Months into Bree and Daniel's running away, it was her father who slipped from the grasp of the Order to find Bree and tell her the truth about her life. He left her a secret message, which she eventually discovered after trying to contact her great uncle Franklin. This message led to their meeting on December 30th, which was also his last appearance. He met Bree at a café and told her, among many things, that she was adopted. Since she showed potential for the ceremony, she had been placed in a "protected home" with him and her (also adoptive) mother. He was killed by Order operatives shortly after informing Bree, presumably because he had defected.

Both hands were clearly visible in his brief appearance, and he wasn't wearing a wedding ring. It is possible that Bree's somewhat unusual remarks about Pluto's new planet friends not having rings in "Poor Pluto" could somehow be a reference to that. His next appearance was in "On The Run", in which he and Bree's mother were directed into a car and driven away by Lucy and a Deacon.

In The Unthinkable Happened, Bree meets up with her father. They are then at a parking garage, where The Order shoots him, and loads his body into a car. The next video, Bree's Dad Is Dead, says it all. (Since then, fans have been known to irreverently comment that something -- a storyline, for example -- is "deader than Bree's dad".)