I've wandered into some dungeon and encountered some necromancers or bandits. I killed some with sneak attack by bow and some turned hostile and they rush to me and I killed them directly. When I sleep, there are no Dark Brotherhood members approaching me. Why?
Why doesn’t the killing trigger the Dark Brotherhood questline
the-elder-scrolls-iv-oblivion
Best Answer
According to the Elder Scrolls wiki,
Basically any non-essential NPC will do. (Note that unlike in Morrowind, Oblivion's predecessor, you cannot kill an essential NPC, so you don't have to worry about killing the "wrong" person. If an NPC is involved in a quest you haven't completed, you won't be able to kill them.) If you are looking for a specific set of targets, the wiki has a list of them. I've listed a few of the best targets below: