Thelia was a Seeker Vessel pilot from the Rebel Advent and the daughter of a Coalescence commanding a Discord-class Battleship, the Vilysian. She's noted as the first member of the Rebel Advent to make contact with the Coalition, when Coalition allies rescued her vessel, the Augur, being chased by 2 Advent Loyalist Disciple-class Frigates.
Thelia was out on patrol when the Advent Loyalists attacked the Rebel Advent in force, using technology obtained from Alliance of Unrelenting Darkness derelicts. She was locked out of Rebel Space, when the primary Coalescences of the Rebel Advent locked down Rebel Space, not allowing any rebel Advent ships to enter or exit, due to the invasion. Thelia, however, traveled too close and a pair of Advent Loyalist frigates attempted to chase her. Thelia sent out a distress call, and it was responded to by a group of vessels, consisting of Celeste Petri's ship, the XB-2000 Retaliator, a Collector Cruiser controlled by Collectors led by Tulinal, and a few Hellcat Squadran patrol ships.
When the group took Thelia to their base, she explained the situation going on currently in Rebel Advent space. While Coalition Command was initially reluctant to interfere, Thelia's distress and psychological pain at feeling her people being killed led IceBite to pressure the Coalition Council into acting.
Once the Rebel Advent was contacted, they sent Thelia to live among the Coalition on Earth, and to be the "eyes, ears, and voice of the Unity" on Earth.
As with most of the Advent, Thelia is interested in expanding her capabilities. As the pilot of a Seeker Vessel, she is curious and an avid explorer.
Due to being one of the Rebel Advent, she has a link to their Unity: if large numbers of Rebel Advent members are killed, she feels it, and is visibly affected by it.