Skyrim General

[Proton]

That's pretty useful information, thanks.

I never tried killing the any other members of the Dark Brotherhood, but I had a member attack me while walking on a road before joining. I think you might be able to though since they got rid of all the rules that were in Oblivion's Dark Brotherhood. I'll test that later and see what happens.

[spoiler]When you first get contacted by the Dark Brotherhood, go to sleep and get sent to the Abandoned Shack (after waking up), killing Astrid instead of a captive will cause you to fail "With Friends Like These..." and receive the new quest, "Destroy the Dark Brotherhood!"
A mission that allows you to kill every member of the Dark Brotherhood.[/spoiler]