There's some excellent NPC cards with associated Houserules located in the GitP 5e forums. Hemeth is one, and he gives the PCs some interesting abilities to use. Created by Goober4473. The thread is called "NPC Companion System Idea." You can also find a link to them on the Paizo messageboards under the forum "4e and Beyond" in the thread "Out of the Abyss Resources (5e)." Posted by Bookrat.
I'd link it, but I'm new to these forums and can't post links yet.
Been running Oota and I accidentally mislabeled Hemeth a regular dwarf and not a duergar in the chaos of the sacrifice event at Shloppdeloopduhslup. So I rolled with it and made him a dwarf with fiery red hair, claiming the name Hemeth Fireblood who was going to sell a cargo of dwarf weapons to the Kuo-toa before they went all Kalllii-maaa. PC's helped him escape the Prince on his trader boat and Hemeth hired them as bodyguards across the lake back to Gracklstugh (and eventually Blidgestone) in hopes of recouping his loses.
Thing is he's also a crooked conman of sorts and adopted the name and goods of a trader that he and Gorlakk exed out for east profit to sell outside the city Gracklstugh.
Only reason why he is able to even be seen in the dark dwarf city is because he convinced enough people that his name and hair implies a certain lineage to Azer fire dwarves (conman = impressive charisma). But the origin helped add a layer of conflict to the party in the city, especially since of the Gorlakk was expecting Hemeth to come back with a decent load of gold and not a handful of montley crew convicts....and ontop of that Hemeth nearly swindled the party and almost sold the PC's to a Drow slavemaster for a healthy profit.....and last session all but Hemeth got arrested by Gorlakk for assassinating rival Drow emissaries in public for said slavemaster.
So its a big exciting mess but having Hemeth know the town without being too embedded as a duergar let the whole city still feel alien to the PC's when they arrived but added a personal level of drama to all the chaos of the city.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.