Dear Fluttershy,
"Unpleasant and mean" is a gross understatement of your demeanor today. I never expected Mayor to forward a public disturbance report with your name on it, but it's here, written clearly in black ink. I'm still stunned it's here on my desk.
Do you know how harsh you were? You were mean enough for Pinkie to visit me for consolation this afternoon. Yes, Pinkie. Look, zealous leader of a smile cult or not, insulting her intelligence and her career as party planner is amazingly low. And from what she squeaked out amid her sobbing about Rarity, she clearly got some flak from you as well.
I could hardly imagine such blatant cruelty outside of Discord's return, and we both know that you weren't yourself then. It isn't you now, and never was, so if you're still beating yourself up or bound to a chair or something, stop. Straighten yourself up; you are not wholly responsible for your actions today, for someone else prompted you to act that way.
Although neither your letter nor Mayor's report mentioned who or what caused this, I know what happened. You visited an assertiveness workshop held by a blue minotaur with dominance issues, right? He was in Canterlot yesterday trying out his tactics on the nobles; the nobles, in turn, tried said tactics on me today in day court.
Fluttershy, just because someone says something loud enough and in your face long enough doesn't make what they're saying any more truthful. Being assertive isn't the same as being a jerk. The nobles didn't quite learn that after his workshop, but once they met my big stick in day court, they changed their minds. Fast.
I'm happy you came to this realization on your own, however. Really happy, because Brutus the Branch was on a warpath, and it didn't mind smacking some sense in another town. You saved me a trip, and for that I thank you.
You've obviously corrected your relations with your friends today, and you should be quite thankful they were so forgiving. But should you relapse, and Pinkie comes to me again in tears...
We're going to have a good, long talk. Brutus will be waiting.
Sincerely,
Princess Celestia
Hello, Luna. Can I ask you something?
You didn't happen to take anything from my room, did you? Something red and round, about the size of my hoof, resistant to squeezing.
What? You threw it at Discord and lost it?! Great. Just great. Now what am I supposed to use?
Luna, what are you--
...okay, a hug is better than a stress ball.