The three important people cited in the achievement, divided by first encounter and second encounter.
-Cultist Scribe in Tower of Estrod, Kenabres: Go before the attack on Defender's Heart, you can find Greybor hanging around here, clear the area of enemies and go to the lower section, you will find the most dedicated scribe you could ever see, a great trickster material, save him from himself by making him cough out the paper.
You can find him again in one of the rooms during the attack in the Ivory Sanctum.
-Traveler Attacked by the Vescavors: Leper's Smile/chapter 2, you can save him right before the attack on the vescavor queen, make sure you have potions/healing spells on you or your team to make sure he is saved.
You can find him again in the Abyss/Chapter 4, Bad Luck tavern, he will reward you with Ashmaker.
Vrock of the Molten Scar: You can find him in the Molten Scar/chapter 3, let him go when you find him, preferably with him giving you the Elven Note that he has.
You can find him again in Ivory Sanctum, before the charge in Xhantir Vang lab where you meet the angels, the open area, go to the opposite direction, you should find a check to make you jump to the other side of the cliff where you can find the vrock again.
Credit to ALEC for their
guide.