Mysterious wanderer and patron of Seres
Bhaal Shem is searching for powerful magical artifacts. One in particular he lost to a certain demon thief you have already encountered. Bhaal made a trade of what seemed to be equitable items, only to discover that his new staff turned into a venomous snake anytime he tried to use it… Not really a big deal, but that does mean the demon made off with his extremely rare, nearly legendary item. Bhaal managed to track the demon to these caves and knows he’s close. He can smell his fear.
Update: Bhaal seemingly caught up to Scratch and dealt with him accordingly. As repayment for her help in the tunnels under Ruisnwick, Bhall gifted Seres a magical cloak. He also sped up her application process at the Seid. Perhaps Bhaal Shem is only interested in helping after all.