|Actor|| Nathan Dales|
George Klimovich (Young Oskar)
|Dates||c. 1661 - 2015 (killed by Rowena)|
|Episode(s)|| 10.22 The Prisoner|
10.23 Brother's Keeper
If you can fry up a decent burger you can get work anywhere. I'm dying to head to Asia. It's just a dream, you know?
– Oskar/Seth, 10.22 The Prisoner
Oskar was the son of a peasant Polish family, who gave aid and shelter to Rowena in 1669, shortly after she abandoned her son and went on the run from the Grand Coven. Over time, Rowena grew to love Oskar, and upon learning that the eight-year old boy was terminally ill, she decided to give the family a gift for their kindness by using magic to cure Oskar, as well as casting a second spell that would take root and make him immortal when he became fully grown.
Oskar would travel all over the world during this time, learning how to cook various meals, even roasting beans to make coffee in Ecuador. By 2015, he'd settled in the United States as a fry cook under the alias Seth, with a desire to visit Asia.
Crowley approaches Oskar, going by the name Seth and working in a diner, and speaks as if he's looking to make a deal with him to fulfill his dream of heading to Asia when he's called away by Sam faking a distress call from Dean.
After Oskar serves a customer some coffee, he turns to place the coffee pot down when he hears a sudden noise and turns around to see Crowley standing in the middle of the room, with every other occupant of the diner unconscious on the floor. Crowley telekinetically immobilizes Oskar, and begins telling him the story of an old witch and a Polish family, revealing that he knows Rowena loved him and gave him the gift of immortality.
Crowley takes Oskar with him to Castiel and Rowena when he delivers the ingredients for the spell to remove the Mark of Cain. When he reveals Oskar to Rowena, she tells him the act is a cruel new low for Crowley, to which he replies that it is only cruel if she actually goes through with it, though he questions who the cruel one would be by then. A visibly shaken Rowena tells Oskar to come and give her a hug, and as he does, she promises him nobody will be hurt, telling him goodbye before she stabs him the neck in tears and spills his blood into the bowl.
After Gavin returns to his own time to restore the fate of his lover, Fiona Duncan, Crowley wanted to know why Rowena stopped him from taking Gavin away to prevent that from happening. She told him that it was payback for making her kill Oskar to remove the Mark of Cain from Dean, so Crowley can witness the loss of a child he loves like she did. By the end, she's brought to tears, visibly shaken with lingering regret.