wait, if Joey's last name is Claire and Jude's is Harley... Maybe they are also half siblings or bluh?

That or Grandpa and their Mom weren’t married when they had Joey so she took her mother’s name and then they got hitched before Jude came along. Or maybe they never got married and just decicded for one kid per last name or some shit like that. Or they could be half siblings and Joey could be biologically unrelated to the Homestuck characters we all know and love, I guess we’ll find out.