Sveinn is a memory of a character introduced in the episode "Broke His Crown." He debuts in an A.I form in Ice King's Crown. Princess Bubblegum and Marceline come across Sveinn when they put on their VR headsets and transport into the Crown's Labyrinth. He is seen knitting and sitting next to Santa.
Sveinn has blond hair down to his neck and shoulders. He also wears a thin headband over his hair. His clothes are green in color, and he wears dark pants. His clothing seems to be old-fashioned, suggesting that he originates far back in the past.