About (watch out, spoilers!)
Setsuna F.Seiei
Voiced by: Mamoru Miyano (Japanese), Brad Swaile (English) (Yuka Nishigaki as young Setsuna)
Age: 16, 21 (Second Season)
Height: 162cm
Birthdate: April 7, 2291
Birthplace: Republic of Krugis
Other Designations: Soran Ibrahim (real name), Kamal Majirif (self-reference in Episode 8)
Unit: GN-001 Gundam Exia, GN-0000 00 Gundam
Having been discovered by Celestial Being at the age of 14 for having special potential as a pilot, he is currently a Gundam Meister for their organization. He can be described as taciturn, and comes off as a knowledgeable young man. Resides in Japan when not on Celestial Being duties.
Setsuna's real name is Soran Ibrahim; Setsuna is his Gundam Meister codename. Six years prior to being recruited into Celestial Being, he was a child soldier in the war-torn Kurdish Republic. He murdered his own parents under Ali Al-Saachez's influence in order to prove his devotion to God, and hence bears a deep hatred towards Saachez. Due to his previous religious brainwashing (and awakening from it), Setsuna no longer believes that God exists within the world. Setsuna believes that war can only be stopped through direct confrontation, and therefore has little tolerance for diplomats and politicians, believing that their "peace talks" only lengthen the conflict and cause more casualties.
Prior to season two, he spent four years working solo, managing to partially repair Exia during that time. He is re-recruited back into Celestial Being by Tieria, and is give the GN-0000 00 Gundam to pilot.
Tieria Erde
Voiced by: Hiroshi Kamiya (Japanese), Samuel Vincent (English)
Age: Unknown (appears to be around 17)
Height: 177cm
Birthdate: December 9th, Unknown Year
Unit: GN-005 Gundam Virtue, GN-004 Gundam Nadleeh, GN-008 Seravee Gundam
A boy with a rare kind of beauty, his history, nationality and origins are all a mystery. Within his gentle tone, he can give a sense of cold intentions. Values the mission above all other issues, including life, and initially doesn't show any 'concern' for his teammates. Tieria seems extremely loyal to Veda, and will go to any length to ensure the secrecy of Celestial Being remains what it is, a secret, even if he has to kill other Gundam Meisters himself to achieve this end. Compared to the other members of Celestial Being, Tieria seems to be more disagreeable, generally not socializing with any of his comrades, and often expressing disapproval of them, including Setsuna F Seiei, Allelujah Haptism, and even his "superior", Sumeragi Lee Noriega. His eyes seem to glow with a digital, rainbow-ish hue when activating the mobile suit GN-004 Nadleeh from GN-005 Virtue. A similar effect occurs when he interfaces directly with Veda. It is implied that he is somehow connected to Ribbons Almark and the rest of the Innovators.
Unlike the other two surviving Meisters, Tieria was rescued by Celestial Being after the events season one and continued to work with them during the four year time gap, piloting the GN-008 Seravee Gundam.
Information taken from Wikipedia.