@Trickquestion
 
Head canon’d.

@Princess♠Molestia  
I mean, she spends all her time in previous episodes saying how much Blank Flanks suck, and then rather quickly lets a Blank Flank into her circle, for no other reason to upset Applebloom.
 
My theory is that her Dad and the Apple Family have been in business for some time, and the children got to know each other at a young age. As Diamond Tiara showed more and more signs of becoming a lazy rich twit, her father expressed admiration for Applebloom’s folksy nature, and wished his little girl could take up a few of Bloom’s positive traits. Thinking daddy didn’t love her anymore, Diamond became a motivated and hard working (she did make the School Paper a huge success) but her father was never quite happy because she retained a cold, cruel edge, based on the popular theory her cutie mark symbolizes harsh, draconian leadership. So now she torments Applebloom and her friends for stealing Daddy’s love.

@Trickquestion  
I don’t think so actually. That might be true actually.

@Princess♠Molestia  
Out of curiosity, have we seen her bully anypony outside of Applebloom and Applebloom’s friends? Becuase the Babs episode made me think that she’s not so much a bully as someone who has a really specific hatred for Applebloom.

So much for the whole “she’ll grow out of being a bully” thing.

Uh huh… and lemme guess, to you ‘business’ is how much money you have to buy frivolous things, right?
 
Yeah…