I was actually firmly on the JBJ bandwagon before and when he beat Rua for the title. I think I even tweeted something about him being an inspirational character because he got the title at such a young age.
Fast forward a few fights and the interviews leading up to them, and I started to really dislike him. There was the 'go get some fans' -incident, and from there his facade just started to fall apart.
I felt a little betrayed to see his true colors, because I thought he was a humble dude. Now I actually root for his opponents on the regular. Doesn't mean that the same thing would happen with DC though, because he's a different personality.
I didn't start hating Weidman, Dillashaw, Cain, Werdum, JDS, Hendricks or any other dudes after they became the champ, so it's not a rule, at least for me. It does put you in the spotlight, and if you're a dick, it will show.