Castti Ch.2 Winterbloom - Plukk was an hard boss!

I thought I finished the second chapter in my previous post, but it was a two part which seems common in this new game (there weren't in the first one). I've just done the Winterbloom part of the chapter 2 of Castti too and it gives a lot more info about her past.
Seems like there is a guy named Trousseau that lived Winterbloom that was an apprentice healer and met Castti at the residence where Melia and Rosa lived. This guy is key because he was in the flashback Sai route of the second chapter too.
Could he be the hooded guy who caused the purple rain to fall down on that village? Seems like the third chapter brings us to that village and...I guess the truth.
There's no doubt that Castti is good, but what caused that hooded guy to do that and destroy the reputation of Eir's Apothecaries? Also how did Castti lose her memories? Questions questions...

By the way the boss fight was a Plukk was a pain to win. The henchman when left alone used some supermove that annihilated my party...