The ghouls to the left and underground dwellers that occasionally creep into the city proper and, well, feed on whatever they can get their claws on.
The athletic rogue featured in the other panel is Jaliel, a cursed thief who has provoked the wrath of some of the underworld heavies that lurk in the shadows. It is worth mentioning that none of the ideas are written in stone. Jaliel's importance is subject to whim of the PCs.
Their association with him, however, has put them at odds with a few people, unfortunately. It will be interesting to see what happens in subsequent sessions.
Although it is difficult to determine in this picture, Jaliel is covered from head to toe in sigils that were carven into his flesh by a vile sorcerer. Jaliel escaped before the sorcerer could skin him and use his flesh for some profane ritual. In addition to having some angry goons on his tail, Jaliel is also stalked by the agents of a very powerful sorcerer.
We'll have to see how this all shapes out. Depending on the interests of my players, these plot lines may or may not develop. While I have my own ideas, the last thing that I want to do is force my players to follow any preconceived stories.
I am actually using the character Jaliel as a PC in a game that I'm involved in as a PC. It is early Iron Age Sorcerer campaign. It is very enjoyable thus far.