Rolf is an immigrant from a far and distant culture known to us only as The Old Country. The most evidence was shown in "No Speak Da Ed." There, it was revealed that he is familiar with a trickster named Gerta who lives in Norway. During flashbacks in that episode, he is seen being chased by what appears to be someone in a wolf costume. Rolf works on his parents' small farm within the Cul-de-Sac and leads a scouting group called the Urban Rangers; a Boy Scout-like group consisting of Jimmy, Plank, and Jonny. Rolf often refers to himself in third person, as well as being the "son of a shepherd," in which he takes great pride. He hardly minds the Eds unless they make a fool out of him or insult his culture, after which he is not afraid to use brute force. When his superhuman strength is unleashed, it rivals Ed's; however, it should be considered that he is the second strongest character in the show, since he was seen lifting a tree with difficulty while Ed can lift a house single handed. Regardless, Rolf's strength depends on his mood rather than his biology.

In multiple episodes, Rolf is shown to have green teeth. As shown in "If It Smells Like an Ed," he has an obsession with jujubes. Rolf, like the other kids, shares the same infatuation with jawbreakers.

Rolf confuses the rest of the kids with his unusual customs, sayings, and food-making. He is one of the few characters who gets respect from all the kids. His best friend is Kevin, and he relates well with Jonny, as he tends to be an outsider as well. Rolf has a very strong accent and is exceptionally hairy. Although he has not revealed his age, he claims that his hair is premature (as mentioned in "Scrambled Ed"). He has a strong liking for meat, and when he agreed on a bet to not eat meat for a whole day, he became severely emaciated almost instantly, not even having enough strength to open the cafeteria door or bite through celery. Seafood is shown to be an integral part of Rolf's traditions in many episodes, particularly in "Dueling Eds," in which sea cucumbers, dead fish and eels are featured, and in "Button Yer Ed," in which Rolf's breakfast feast is shown to be composed entirely of seafood.

Nobody except Rolf and his family knows what country he is from. It is apparently fictional, though often suggested by fans to be a Northern or Eastern European country. Rolf speaks English with a strong accent and also has a tendency to refer to himself in third-person.