Sonia

Sonia is one of Rebecca's party guests as well as a member of the Hymn of One and the ex-girlfriend of Carl Adams. Even after a brief stint working with TAAG to help save Emma, Sonia later returned to the Hymn of One before the events of the Ascension.

Background
Sonia first appears at Rebecca's party with Carl, her boyfriend. While talking to Daniel at the party, she appears drunk. Later at the party, Daniel interrupts a conversation between Sonia and Carl, which Sonia insists is fine. Later, Sonia and Carl appear together with Bree in Sing With Me. This reveals that they are in fact Hymn of One members, along with the fact that they attended the HoO seminar. The two remain close and later appear in the propoganda video Nothing More, Nothing Less, saying that they are "happy and proud brothers and sisters" of the Hymn of One.

In A Family Affair, Sonia appears in tune with her song and devoted to the Hymn of One, as well as Carl. Her appearance in Spreading the Song, however, reveals that she is not content with the answers she receives from the Hymn of One, and wonders if there is any truth to what "those kids" have been saying about her religion. When Carl tells her to shut up, Sonia appears visibly upset with him.

In We All Make Mistakes, Sonia tells TAAG and the viewers that she was in the Hymn of One, but has since saw TAAG's videos and realized how evil it is. She also says that she has information on the HoO that will help TAAG and that she plans to use the information to help fight the Order. Over the next week, Sonia tries to persuade TAAG to steal the Ceremony baby, which they successfully accomplish while holding a Deacon and Watcher at gunpoint.

After this, Sonia was abducted by the Hymn of One, who tried to get her to tell them the location of the baby. At first, Carl attempted to guilt her into spilling her secrets, but she accused him of being a pawn of the Order. At this point, a Hymn of One official (implied to be Chris), beat her to try and get her to tell. She returned to TAAG in bad shape, and warned them that Carl has become a part of a new project being run by the Order, though she wasn't aware of the specifics. During her stay, Sarah accidentally told Sonia that Emma was sending a code to them while in Claire's captivity.

After this, Sonia is not seen of mentioned for weeks. It was revealed in the Jonas Conference Call that Sonia left the TAAG and had not left any method of communication behind. Months later, Sonia returned, apparently "reborn" as a Hymn of One member. She said that she had lost her way, but she had found herself again in service to the Hymn of One, and urged others to join so they could take part in the celebration of the Eclipse.

Etymology
Sonia is the Russian diminutive form of Sophia, ultimately coming from a Greek name meaning "Wisdom."