When a unit affected by Hostile Takeover is retreated, who exhausts the rune and where does the unit go?

Ruling: When a unit affected by Hostile Takeover is retreated, the owner (the player whose deck the unit came from, not the controller or the owner of Hostile Takeover) exhausts the rune, and the unit returns to its owner's hand.

Nuances:

• Owner and controller are different: the owner is the player whose deck the unit came from, while the controller is the player who currently controls the unit and makes decisions about it.
• Control of a unit can change during a game, but ownership does not.
• For tokens, the owner is the player who controlled the source that played the tokens.