|"Everybody knows Harley, and Harley knows everybody. That's his job: knowing things. He's the man on the streets, the guy on the inside, the one who looks like he just crawled out of a sewer, but who's just as likely to have been in some general's office.
Don't get the wrong idea. Harley isn't someone who lives in a penthouse an goes slumming for info. He's the real thing. He knows the people who live in the tunnels because that's where he spends his time. He hangs with the ex-soldiers who have gray death, and he learns everything they know... and they know a lot. He chats up local hookers, bums smokes off the NSF guards, does odd jobs in the down-and-out bars, and in general, lives real life up to the grimy, crusty hilt. You can trust that his information will be accurate, for the right price. "
|— description of Harley Filben, Deus Ex|
JC Denton meets Filben again in the Battery Park subway station. Here, he agrees to give JC the code to access the Brooklyn Bridge Subway Station (where the NSF hauls Ambrosia and other supplies to their base in LaGuardia Airport), if he is paid.
On the second return in New York, Filben can be found in the Underworld Bar and he'll inform JC about the UNATCO raid. however the two won't make any conversations.
On JC's third visit to Hell's Kitchen, Filben is found in the Underworld Tavern. He reveals to JC that he was affiliated with the NSF all along (confirming the reason for his concern for Gold), and informs JC (with evidence) that the Midnight Sun reporter, Joe Greene, is really a UNATCO informant. In another astonishing twist, Filben reveals himself as a triple-agent; he works for UNATCO, the NSF, and the Illuminati. JC asks him for Stanton Dowd's location (with success).
- Filben can be completely avoided until JC's return to New York the third time. While this will change the conversation somewhat, the outcome remains the same; while this makes sense for gameplay and plot reasons, it's rather strange that Filben would set up a meeting between a complete stranger and one of the leaders of the Illuminati.
- It's arguable that Filben's request to kill Greene is so that JC can prove his loyalties.
- It's also possible that Filben, being an agent of the Illuminati is in the loop for JC's anti-MJ12 activities, and knows of him even if he never met him.
- The conversation with Filben in Battery Park will also be slightly different if JC never rendezvous with him on Liberty Island.
- On the second visit in New York, Filben's lines won't be different if JC met him before or not.
- When meeting Filben in the Subway Station in Battery park, if JC continues trying to talk to him, he will mention that a lot of people are on the payroll of the NSF "including some of your buddies at UNATCO" but he refuses to reveal who, implying he know about Paul's true affiliations.