Data on lone DB agents:
Alval Uvani, Dunmer battlemage, and secretly a Dark Brotherhood assassin, and Black Hand member. Has a house in Leyawin, travels between Leyawin, Skingrad and Bruma. Ausually home on a Sundas.
J'Gasta, Khajit Unarmed specialist. Also a Black Hand member. Terrifying in a fight. Has a home in Bruma.
Shaleez, Argonian fighter and Silencer on the Black Hand. May or may not be holed up in a flooded mine north of Bravil.
Ungolim, Bosmer archer, and one of the Listeners of the Dark Brotherhood, their highest rank. Probably stronger than us.
Night mother, Freaky undead witch who may or may not have got freaky with the god of the void. Interred beneath the statue of the Lucky Old Lady in Bravil. Co-ordinates the Dark Brotherhood's customer acquisition via prayers to her.
Hvalfstein Hoar-Blood, Nord berserker. May or may not be camped on Gnoll Mountain, east of Bruma.
Lucien Lachance, Speaker of the Dark Brotherhood. Handles recruitment. Lives in
Fort Farragut, north of Cheydinhal. No easy fight.
Mathieu Bellamont, Crazy Breton assassin. Hangs out under the lighthouse in Anvil. Talks to his late mother's skull, is batshit insane, and has a plan to wipe out the Dark Brotherhood via killing the Night Mother. Will fail if things remain as they would have been. Probably best left to last.