If you kill Renal and make a Hit and run strategy just to steal whatever Renal has, Arkanis will always be there waiting for you in the docks. That say, if you made alliance with shadow thieves. You will never be able to see the Dwarf who make CromFyer or the vorpal blade and all the artefacts. I heard you can kill Gath if you are with the vampires. I did that error and restart a game 'cause I wanted the red D armor and could not make it to the dwarf because I always die before reaching the store in the docks ...
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Maybe it's because I hate drows more than I hate Humans - Jarlaxle to Entreri