In order to unlock the ‘Seeing Things Differently’ achievement, you first have to unlock an alternate narrator. There are two ways to do this:

• Firstly, to unlock “Druth,” you simply need to find all 18 Lorestangir (which you need to do for Tales of Midgard (100G) achievement anyway).
• And secondly, simply completing the main story will unlock the “Others” narrator.

Then, you just need to go to Settings > Audio > and under Narrator at the top, choose one of the two aforementioned options. Then, go to Chapter Select and choose any chapter. Do that and the ‘Seeing Things Differently’ achievement is all yours.

Incidentally, you can also watch either the Landdisasteinar Stories or Lorestangir Stories in the Extras menu too, which is how I got it. And presumably, you can exit the game after getting the 18th Lorestangir to “unlock” the option in the game’s settings, then change it at the menu and load back in - meaning you can get it in your first runthrough.

Either way, it’s super easy.