About (watch out, spoilers ahead)

Who're are Regene and Tieria?

x Codename: Tieria Erde (ƒeƒBƒGƒŠƒAEƒA[ƒf)
x Real name: Unknown
x Seiyuu: Kamiya Hiroshi
x Birthday: December 9th, Unknown year
x Age: Unknown
x Height: 177 cm
x Nationality: Unknown
x Allegiance: Celestial Being
x Gundam: GN-005 Gundam Virtue, GN-004 Gundam Nadleeh, GN-008 Gundam Seravee

A young man who has a rare kind of beauty and a sharp tongue. Everything about his past, including origins, age, real name or nationality are all a mystery. He's the coldest of the Meisters and values the missions above all other issues, including his own life or his comrades', and at the begining, he doesn't show any concern at all.
He is extremely loyal to Veda and believes in its word more than in anyone else's.
He can interface directly with the Supercomputer named Veda which apparently gives the agreement or disagreement for the Meisters' missions, but after encounter a fight with the Trinity sibilings, he becomes unable to interface with Veda. This makes Tieria realize they can't trust in Veda's words anymore because it had been hacked.
Even though his cold personality seems to change after Lockon gets injured for protecting him during episode 21, and also after Stratos' death in episode 23.

However, in the Second Season we can see a more mature Tieria, a Meister who's changed a lot thanks to Lockon Stratos. Right after episode 25 of the First Season, Tieria locks himself up in his room and refuses to eat or see anyone. He thinks he's failed and now most of the crew are gone, so he believes there's no hope, until what we could call "the Ghost of Lockon" appears before him and tells him not to give up and to change the world. Then Tieria proposes Ian and Feldt to rebuild Celestial Being and find the lost Meisters, Allelujah and Setsuna.

x Codename: Regene Legetta ( ƒŠƒWƒFƒlEƒŒƒWƒFƒbƒ^)
x Real name: Unknown
x Seiyuu: Paku Romi
x Birthday: Unkown
x Age: Unknown
x Height: 177 cm
x Nationality: Unknown
x Allegiance: Innovators
x Mobile Suit: Unknown

Regene is an Innovator who resembles Tieria a lot. His physical appeareance is almost the same as him. With a tongue as sharp as Tieria's but also with a way delicate way to say things, Regene seems to be the closest being to Ribbons Almark. Regene is, however, like a kid. He seems to care a lot for Tieria, despite the fact they have different allegiances, and after meeting him in episode 8, Regene takes a bigger interest for his "lost twin". We can see further in the series that he is, above all the Innovators, the most loyal to Aeolia's true plans and starts to see Ribbons with a different look: he does no longer trust him or his intentions; this is why he sort of betrays him by giving Wang Liu Mei the true location of VEDA so she can leave it in Celestial Being's hands. However, Ribbons discovers this and warns Regene not to act in that childlish way again or he would suffer the consequences. But it doesn't seem Regene will give up that easily...