No_one

Alternate explaination for bringing Lilah to Sunnydale could include Wolfram and Hart seers getting a hint of the Mayor's plans and they send Lilah to investigate him or just outright give an ultimatum. Faith then decides to take care of Lilah on her own to help out the Mayor. Ultimately, if you wanted to remove the Mayor from the story, this could lead to Wolfram and Hart taking offense to losing one of their own and they retaliate against the Mayor.