The Shadowlands

[AU] When Terra is finally able to leave his stepfather's manor, he vows he will never look back. He keeps this vow until a dying Xehanort demands his return. Grim circumstances force him to return with Aqua to attempt to gain closure and his inheritance, but will all the greed, temptation, and darkness cause him lose himself and Aqua to his half-brother, Xemnas, in the process?