Seal Away and Permanent control
The Seal Away will return the creature under its owner's control: a permanent enters the battlefield under its owners control unless specified otherwise.

610 One-Shot Effects
610.1. A one-shot effect does something just once and doesn’t have a duration. Examples include dealing damage, destroying a permanent, creating a token, and moving an object from one zone to another.
...
610.3b An object returned to the battlefield this way returns under its owner’s control unless otherwise specified.