It is Yocun that you see at the start of the Zanarkand Dome.

Anyway, I would like to point out that Anima is no different to any other FA. If seymour had used her against sin when he was a kid, he would have died if the aeon was successful. The fact that he didn't use her aganst sin allows him to treat it like a normal aeon, up to the point where he made a temple for her and shows her off in Luca. Even now in fact, if seymour used Anima against Sin, he probably wouldn't die as the bond between him and his mother would have died with time so Anima becomes just another Aeon.