faustling:

They had all met during the ordeal with the Titans of Myth--some before then--and decided collectively that they should talk.  Percy didn't understand the intentions of the others, but he was there as requested.

underthehood:

Marcus had been getting a lot of activity to suggest that something big was up with the Gotham crime families. Though what he had not been about to beat out of anyone yet. Whatever it was is was the small fish didn't know what it was so he needed to go fishing for a bigger fish which of course would require a bit more planning.

There was a lieutenant that he had in mind that would do nicely and should know what's up. But getting to him would be tricky as would be the interrogation but was definitely something he could do.

He was standing on the opposing rooftop of the building he would need to get into making sure he was all set and ready to go. He wanted this to go as smooth as possible.