what to do with sarin's skull

a secret quest in the sewers. it is not marked at the journal, but it can be completed, and i'll show you how

intro

when you come to the sewers you can find several strange npcs: a paranoid madman, who hangs out with mephits and mud golems, and the other, who can't talk but can trade with you.
from the first guy, Aelis Siryasius, you can learn that they all were a gang at one point, and fought the absolute, and they had another member, Sarin, who they had to kill because she allegedly joined the absolute cult.

the hidden quest is about that Sarin. you need to find Bareki, the silent former gang member, who is now located near the Bhaal temple entrance. loot the pouch behind his back and find Sarin's skull there.

what to do with Sarin's skull

if you loot Sarin's skull you can see that it is a quest item, and that now her headless spirit is following you. this quest however is not marked in your journal (at least at the moment of this guide creation).
here is what you should do with the skull.

[/ /\ (ರರ⌓ರರ) /\]

i am still finding new stuff too, after almost 700hrs)

[Squid]

Thank you for the information. I only just started a second play through and am on Act 3 in my 1st and literally found so much shit I didn't before Dx