Princess Emeraude is the "pillar" of Cephiro, whose prayers can effect the entire world of Cephiro. In a certain way, Cephiro is a reflection of Princess Emeraude's heart. When Emeraude falls in love with Zagato, she is unable to concentrate on her prayers anymore and as the result, Cephiro becomes twisted by chaos, overrun by monsters and wars. Emeraude's age is thought to be quite old, but she always appears to be a little girl.
The seiyuu who brought the character of Emeraude alive is the talented Japanese Megumi Ogata, who has made a succesful career as an artist in Japan.
Aelita is similar and different to Emeraude at the same time. Aelita, in S1 and S2, is regarded as a part of Lyoko, and is sometimes as the pillar of Lyoko. Emeraude is the "Hashira" ("Pillar") of Cephiro. Aelita's love for Jeremie does not affect Lyoko's stability much, but if Emeraude falls in love, Cephiro slowly crumbles and dies.