R4

R4 is the decendent of either Arthur, D.W., or Kate Read. He lives in the future and was seen in the opening and ending of "Background Blues." Like Arthur, he easily gets annoyed by his sister, 3W. He also has a pet dog, Hal. When he and 3W were arguing over a game of Virtual Flingee, their mom had them watch a datagram (video) of the episode.

Appearance
R4 wears futuristic clothes with a tan shirt and blue tights. He wears either a red hat or helmet that his ears stick out of. Despite the future's advanced technology, he wears the same kind of glasses that Arthur did.