Diamond Tiara is perfection incarnate. She usually gets whatever she wants from her father, and whatever she doesn't have she's incredibly skilled at just taking.
However, being forced to work with Apple Bloom on a group assignment as punishment was not on her wishlist.
Neither was getting lost deep in Everfree with the aforementioned blank flank, pursued by timberwolves and any number of disgusting creatures that refuse to bend to her will, and ending up stuck tending to an injured filly that she just can't bring herself to leave for the forest to claim.
Maybe the jeweled tiara on her flank means something more than she'd expected.