The players haven't gotten there yet. But when the "reveal" comes about. The BBEG is going to be a sentient tree that possesses people via its fruit. The players have been fighting their way through low level gang members, various corrupt cops, a few corp types with security, and into a research facility. I am going to love the look on their faces when the final door opens and in the middle of the botanical garden is a huge twisted tree. Surrounded by white lab coats tending to it. They are going to be yelling things like "protect the boss", "don't let them hurt the boss", all the time throwing themselves at the party with a zealot like glee. After the battle. The players will look around for the "boss". If they don't put two and two together, then the tree can come after them later, after it gets new minions of course. *insert evil laughter here*