First off, we have to deal with the fact that a Patterson is someone who thinks that a friend's job is just sort of live one's life in a holding pattern until he or she is called for. (You will note that this makes Elly into one of Michael's friends.) This not only manifested itself in the off-putting whining about how awful it is that Connie and Lawrence aren't home, it explains the insane and sullen jealousy Liz had of Shawna-Marie. Simply put, Dawn was a stinky, no-good traitor for living her life while the Breath was at Exile Farm for the summer.
This leads nicely to the whole "casual betrayal for a sordid and stupid reason" malarkey that always seems to happen when they make the mistake of irritating one of the Sainted Patterswine. Liz spent days treating Dawn like a leper because she felt left out and, well, most of the reason Lawrence is estranged from his parents because Mike stupidly told him "out yourself to your folks when it's pretty much guaranteed to backfire on you or we can't be 'friends', you disgusting deviant." Luckily for Lawrence, his friendship with Mike died so he doesn't have to endure his nonsense any longer.
The problem is that his friendship with John and Elly hasn't so he's still expected to provide stuff at below cost so as to display his gratitude. Other victims are Gordon, Annie and anyone else who they can turn into a blasted vending machine. The fun part is, of course, that having to reciprocate any of this means that the person doing it is a greedy, manipulative monster who either expects them to be enslaved to her family politics or wants to crush them with her star power.