In the mission where you must assassinate/brand the High Overseer, to get to Samuel you need to go across the backyard. You may remember it because one of the Overseers are killed by his allies there, due to one having the plague.
That is the building that I start at with these directions, and I get on the roof.

I turn left, and there is a tall building. I look slightly upwards, and on the balcony of it is some mysterious figure. If I try to look directly at it, it teleports away, so I recommend quicksaving before you look at it.
Has anyone got a closer look? Can they provide information on it, perhaps a screenshot?

I really wonder what that figure is, it's really creeping me out