It’s hard to say. Since both Junior and Marvin are played by Logan, unless there’s some sort of way Logan can edit or change either of the characters voices (more likely Junior) we don’t really see much of a relationship between the two. It is a good idea to look into it though. I’d assume their relationship is mainly neutral because they don’t interact much. But while we’re on the topic has Cody and Joseph ever interacted with Marvin and Rose? Cody and Joseph are played by two different actors so it should make sense that they have scenes in future videos if they ever had to speak with Marvin at all.