I think it best to provide you with some details about the Dark Brotherhood before I continue with the story.
There were three Sanctuaries in Skyrim - one in Dawnstar, one in the forest near Falkreath, and one hidden in a mountain near the centre of Skyrim, Whiterun. The latter Sanctuary is the one I had spent the last twelve years as an assassin for.
The life of an assassin reaped more rewards than one would expect - gold, of course, came in copious amounts. It provided outlets for this with murderous intentions. And then there was the fear.
Fear grants you power that nothing else can - who else but a killer could walk through a busy street in a well-guarded city, wearing the armour of a Dark Brother and carrying stacks of weapons, and yet have the city guards do nothing more than to assure you in hushed voices that they know who you are and yet will not attempt to arrest you? Of course, every now and then there'd be a younger, stupider guard who'd get you alone and try to finish you, but when their bodies were found by the next patrol it only added to the intimidation that radiated from those who worked for the Brotherhood.
As for how one could contact the Brotherhood, there was the Black Sacrament, in which one would create an effigy of their intended target out of human body parts, surround it with a circle of candles, and then stab the effigy while uttering the Black Sacrament chant. The Night Mother, leader (for want of a better word) of the Dark Brotherhood, could detect when, where and by whom the Sacrament was performed, and would inform the Listener, a person who had the high honour of being able to hear the voice of the Night Mother. Unfortunately, the Night Mother was not currently at the Whiterun Sanctuary, and even if she was, no Listener was currently known to exist anyway. Instead, we had members of the Brotherhood placed throughout the nine holds - when someone performed the Sacrament, the Brother or sister in that hold would find out and inform us.
