this is based on the game and will give spoilers so dont read if you dont like spoilers
His name is Kratos, he is a young imperial. he was just a beggar, living on the street. he found a dagger and started a career of mugging people that dare walk the back alleys in the imperial city at night. one day he started thinking about not just threatening the persons life, but to take it. and that night he started sneaking around the back allys when a elf started down the ally, he jumped out of the shadows and stabbed the elf over and over and over again and took the elves septims and ran. he went to his home in the waterfront, (the abandoned house) he stared at his bloody knife and small pile of septims. he went to sleep on his bedroll dreaming about his kill and then he felt the air get colder and he felt a hand touch him on the shoulder, startled, he stood up and there was a man clothed in black robes and he spoke to him, the man gave him a offer to take up a life of murder or to go back to his life on the streets, he took it. he was told to go the a inn in the middle of the wilderness and kill a man. he went to the inn and started asking around and he found out that the man lived downstairs, he went downstairs to find a man sleeping, he walked silently to the man and plunged his knife in his neck, after a short struggle the man went limp and kratos left the inn and headed back to his home. that night the robed man came back to his house and welcomed him to the dark brotherhood.
this is chapter 1 there will be lots more so stay tuned.