It isn't uncommon to see people sitting on these stairs. People sheltering from the never ending rain, kids sitting down to have a smoke or drifters resting their tired legs.
This person is no different. He or she will sit on the stairs seemingly lost in thought. There is something sad about them, though you're not quite sure why you think that. They seem lonely. You almost feel sorry for this random stranger.
But they are blocking your way to the door at the end of the stairs and you want to get inside, to your warm home. As you step forward they will look up at you and ask for a small favor. Something that in no way would inconvenience you. Maybe they'll ask for a lighter for their cigarette or directions to the nearest bus stop.
You don't have to help them at all. You can walk right through them as if they were a ghost. But when you look back at them, you'll see that their mood has changed. They still seem sad, but could it be that they feel sorry for you now?
Well that's because you just made the same mistake they made, a long long time ago.