> Hmm.  Younger poster on the forum starts a thread:  I keep seeing a guy outside my window.  He's there and then he's gone.  Tonight I watched him as he opened some kind of, um, portal, and went through.  I couldn't see anything else.  It's the arched gateway leading into the chapel across from my apartment.  It's so fucking creepy.  Every night he's been there, in a red rain jacket with some sort of dog following him.   They both go through.  I wonder where it goes. 
> 
> And enter Lauren. And possibly super secret sin eater FBI agent. There are traits that would indicate that it is a Changeling, archway, portal, ya ya. 

Lauren shows up, investigates the area, and is thoroughly confused to find absolutely nothing that would indicate a gate to the Underworld--no ghosts, no sick feeling in her stomach, no rivers of blood/pestilence/scorpions----so she decides to sit on the curb and fade from view (via Stillness Shroud: she's not actually invisible, just really hard to notice or remember) and see what happens. New supernatural stuff is always exciting!

Let's say when the guy described in the forum post shows up, she follows him, watches him open the gate, and interrupts him before he can step through. Something like walking up a few paces behind him and clearing her throat before asking, "Hey, um, that's a really neat trick! What is it, exactly?"