Spoiler Alert! Warning: Game spoilers up ahead!!
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Cicero and the Dark Brotherhood Spoiler- A lot of you have seen Cicero, the psycho jester, on the side of the road in front of Loreius Farm with a broken wagon. (Delayed Burial quest) He claims that the coffin in the wagon contains his dead "mother" in it. He wants Vantus Loreius at Loreius Farm to lend him his tools but Vantus isn't too sure about Cicero so he asks you to tell a patrolling guard that Cicero has weapons inside the coffin to get Cicero arrested. You have two choices, help Cicero, or tell the guard he has weapons. Help Cicero: Can later lead to Cicero being a follower and you can possibly get his outfit. He also will like you more if you join the Dark Brotherhood. Tell Guard: Works well if you want to complete the quest Destroy the Dark Brotherhood! instead of joining the Dark Brotherhood. Here is where the REAL spoiler comes in. The coffin that he claims to have his "mother" in it, actually contains the dead Night Mother from the Dark Brotherhood. You actually see Cicero again if you join the DB because he delivers the Night Mother in her coffin to the last DB Sanctuary in Tamriel. Her burial place in Bravil was destroyed and (believe it or not) Cicero is her keeper. I like to call Cicero the Creeper Keeper because Astrid gives you a quest (Whispers in the Dark quest) that requires you hide in the Night Mother's coffin in order to spy on Cicero. Cicero has been heard talking to someone after locking himself in the NM's chamber. You actually get to see the NM when you climb into her coffin. (Skyrim is 200 years after Oblivion and the NM was around then so the NM's body is at least 300 years old) The NM starts talking to you and gives you a quest and it turns out Cicero is just being his psycho self and talking to the NM. You are called the Listener because you are the only one that is able to talk to the NM.
Don't worry, there's more spoilers to come!