Infernax

First, you will need to become evil, which you can find in this guide:


Next, you need to listen to Hans' story, which is in this guide:


Here's a written walkthrough though.

1. As you finish the quest to becoming evil, and are still in the Arkos hideout, talk to a guy in a robe.
2. They will start a quest, asking you to kill Hans. Go to Darsov.
3. Enter Hans' house and listen to him. You will need to keep pressing "listen" for a long time until you can't anymore.

This achievement is not possible to get in a Good playthrough

It is story related when you're doing ultimate evil playthrough

Once you are evil enough you will get the password to the hideouts you will get a quest to kill him from one of those red hooded guys in the hideout just above Arkos where all the shops and people are

When you go to kill him in Darsov, he will start pleading and telling you a story
Keep clicking on listen, a lot, boy can this guy talk! You will pop this cheevo once the slay or spare option comes up