Perhaps they could also find a half-completed sacrament like the one in Maven Blackbriar’s house in Riften and use that instead.

For example, not only could there be someone who was trying to summon the assassins personally like Aventus Arentino in the Innocence Lost quest, but the game could include texts that players can find that might lead them through performing the Black Sacrament themselves. There should be different narrative-driven options in the game for finding out about the Brotherhood. The Elder Scrolls 6 should explore some alternate possibilities for triggering main questlines like the Dark Brotherhood's. Oblivion went a more dynamic but less narratively interesting route, where the player would be visited by Lucien Lachance in their sleep if they ever murdered an innocent and got away with it.

In Skyrim, there is only one way to activate the Dark Brotherhood questline, which is by visiting Aventus Aretino in Windhelm and taking up his contract for him.