Dark Brotherhood is, in other words, the Assassins Guild, a secret group that specializes in killing for money.
To join the Dark Brotherhood, you will need to kill someone. This Oblivion Walkthrough will also cover how to murder someone to summon Lucien Lachance and then how to find the Inn of Ill Omen and kill Rufio quietly to gain entrance to the secret assassin's guild. Joining the Dark Brotherhood opens up its own questline with the ability to gain unique weapons, armor, and followers.
By completing Dark Brotherhood quests, you will also gain a reliable black horse with glowing red eyes named Shadowmere.
