not really in the earlier seasons...they barely interacted prior to season 6 (that 1 season 5 episode aside...)
anyways, interesting theory, but it's hard for me to imagine that Dewey is, um, a young Francis time-traveling forward when we've seen the story of his birth, as well as at least 1 flashback of a Dewey-aged Francis (in "No Motorcycles") who looked nothing like Dewey...
You are right Cadet, I used the wrong words, maybe the most "positive" is what I am looking for!!!. I don't feel any negativity between them, also it seems Dewey is worshiping Francis in Season 1, he is the older cool brother.