After completing The Assassinated Man, you will take orders from Ocheeva. Ocheeva is the female Argonian in the Dark Brotherhood and seems to be a bit humbled by your skill.
The Lonely Wanderer
You will need to kill a High Elf named Faelin in the Imperial City, but little is known about him within the Brotherhood. Find and speak with the first High Elf you see in the Imperial City for info on Faelin. Their most likely response is he resides in Tiber Septim Hotel. If your High Elf doesn't know, find another one and ask. Find the Tiber Septim Hotel in the Talos District and talk with the proprietor about Faelin. She most likely won't give you much information unless of course you already have a high disposition with her, if not, raise it. She reveals Faelin is a junkie, doped up on Skooma and infact does live there along with his fair lady. He visits her for a couple of hours in the night before heading back out to get high.
Go upstairs, if Faelin is there and you do want the bonus, DO NOT KILL HIM. Faelin and his girl's room is the first door to the right. Talk to Atrena and max your disposition with her, so she tells you where Faelin gets high. Head over to The Elven Gardens and follow your quest marker to Lorkus's House. Once inside Lorkus's house hunt down Faelin and slay him. Talk to Orcheeva back in the Cheydinhal Sanctuary for your reward, The Shadowhunt Bow (if you killed him alone) and 100 gold.
Roderick, the leader of a band of mercenaries, has fallen ill, but his comrades are keeping him alive through a powerful medicine. Orcheeva will ask you to go to Fort Sutch and poison him by swapping his medicine with her poison. If you're detected at all while in Fort Sutch, your bonus will be unattainable. The Fort is North of Anvil, so if you've never been there, that is likely your quickest access point.
Entering the fort, look for a gate to the right. After picking it and heading through, follow the tunnel up stairs to gate that is locked. A guard patrols here, and sneak around in the shadows right, quickly passing two locked gates, head through the opening on the right. Up stairs, follow the right path and your quest marker. You'll eventually come to the room where the medicine is kept. The cabinet put the poison in the cabinet and take the medicine out.
- The poison is not kept with the rest of your poisons and potions, it is at the bottom of your miscellaneous inventory.
Now get out of Fort Sutch, remaining undetected as you do so. Fast travel to Cheydinhal and talk to Orcheeva for your 200 gold and The Deceivers Finery. If you were detected or had to kill Roderick yourself, you will only get 200 gold.
This is a fun quest. There are five people, you must kill, and they are all locked in a one house of their own free will. They were told to search for a treasure chest with gold and the key to the house. The catch? There really isn't a treasure and the key is with the assassin sent to kill them...you, but none of them know this. If you manage to kill them all without being identified as the assassin, you'll receive a bonus. Speechcraft can make or brake you in here.
Head over to the house and talk to the doorman. He'll give you a key and lock the door behind you as you enter. First talk to everyone, and max out your disposition with all of them. Now, target the guy that went to nap upstairs, sneak attack him and kill him quickly. The Dark Elf should come in, if you tricked her into thinking that your first target was really interested in her. Close the door behind as she enters the room and then slay her. You can talk to everyone and watch their reactions, this is were the fun comes into play. You can play with their minds and make them believe someone else is the killer, though they don't suspect you.
Next go talk to the old woman, tricking her to go where no one else is. Kill her at your first chance. By now, the Nord should be nice and drunk, so just talk to him and agree that you think that the other person is the killer and he will go after them. Follow him and after he kills the elf, or vice versa, kill the remaining person of the house. You're now free to leave. Return to the sanctuary, talk to Orcheeva and for your reward, 200 gold and The Night Mothers Blessing bonus.
Adamus Phillida, former head of the Imperial Guard who made life difficult for the Brotherhood has recently retired. Ocheeva will ask you to kill him, giving you a Rose of Sithis, an arrow that will kill its intended target, however, it doesn't pierce armor. You would think killing Adamus with the Rose was your bonus, but its not, Ocheeva want you to send a message in a rather disgusting way if you want the bonus. Once you kill Adamus, cut the ring finger from his hand put it in the desk of his successor, in the Imperial City.
Adamus can be found in Leyawiin, and thats not all, the guard has a bodyguard. Makes sense, right? He usually hangs out in an inn or in the City Watch Barracks. Adamus also likes to go swimming during the day, leaving him exposed without armor. The perfect chance to stick him with the Rose of Sithis.
Go to the pond in town and wait until noon. now sit tight and wait for Adamus to show up and remove his armor for his daily swim. Equip your bow and Rose and take the shot first chance you get. Go over to the corpse and remove the finger and everything else from Adamus. Fast travel to the Imperial City Prison. From your location, sneak over to the Imperial Watch Office, and open the door with Adamus' key. Walk over to the desk, pick the lock on it, and drop the finger in the drawer.
If you get caught in a break and entry, just make sure you get the finger in the desk before the guards make it to you. Once you're out of the office or the prison, head back to Cheydinhal's sanctuary and speak with Orcheeva. You'll receive some gold (up to 600) and an extra 500 gold for the bonus, and a promotion. Congratulations, Assassin.
Of Secret and Shadow
This isn't so much a quest as a changing of the guard. Ocheeva tells you that Lucien Lachance wants to talk to you and hands you a note. Read the note and it tells you to meet him in person away from the sanctuary and not to show the note to anyone else.
Now head out of town and go to the base where Lucien wants you to meet. Don't head inside though. Walk around the base and look for a large hollowed out tree. Inside is a trapdoor leading straight to Lucien without going through the Skeletons and Ghosts on the way to him.