The amount of information one does NOT have about Finn could (and probably does) fill a normal sized encyclopaedia. Having emerged from one of the passages (which one was not registered), Finn scared and enchanted people in equal measure. A full sized silverback gorilla, but with the eloquence, intelligence and accent of an Eton-educated boy, people didn't really know what to make of him.
Finn is somewhat of an adventurer. He has a small company working out of Steamville 'Wallington and Associates', which is effectively a mercenary/exploration set-up. If you want protection, or to explore a Place, this is the place for you. They might not be cheap, but by golly they get the work done. They try to shy away from pure slaughter assignements, but were right there in the front lines on I-Day.
A request character. Smart, curious, and really strong phisically (Big) which gives him a bonus for strength, but makes him easier to hit (because he's huge).