Kill an innocent NPC
Sleep in any bed
Wait for Lucien Lachance to visit you
Accept his offer to join
Complete the contract on Rufio at the Inn of Ill Omen
Return to Lucien Lachance
Go to the Cheydinhal Sanctuary and enter the Dark Brotherhood
Kill an innocent NPC
Sleep in any bed
Wait for Lucien Lachance to visit you
Accept his offer to join
Complete the contract on Rufio at the Inn of Ill Omen
Return to Lucien Lachance
Go to the Cheydinhal Sanctuary and enter the Dark Brotherhood