You must be playing as a neutral character in order to be able to ask Butch to join you and to receive a confirmation from him that he'll follow you. The exact location of Butch is Rivet City - Muddy Rudder. This means you had to get rid of the Overseer and to convince Vault 101 citizens that it's safe to leave the crypt. Butch can be found in Rivet City, but only if you've chosen the best outcome to Troubles on the homefront subquest. Obviously if you decide to give the violin to Abraham, you won't be able to complete the old lady's quest. The only exception is the Soil Stradivarius - violin for Agatha ( Agatha's song quest) found inside Vault 92. Most of these items can be found inside The National Archives and Museum of history. Aside from the main assignment, Abraham Washington from Rivet City - Middle deck can reward you for bringing him artifacts tied to the history of the United States. There are a lot of useful items in the area. Destroy it and explore this room carefully. You'll find a single defense turret inside the room. You might be able to open the hatch, but you have to raise your lockpicking skill to succeed. If explore the top level of the bridge tower you should notice a sealed hatch. Ronald can be found in Girdershade ( Nuka-Cola challenge quest). Remember the naughty nightwear you found in Marigold Station? You can give the lingerie to Garza and he'll ask you to bring this item to Ronald Laren. Sadly, she won't give you anything in return, so you're doing this for your personal satisfaction. You can also travel to Shalebridge (the queen can be found in Shalebridge tunnels - hill) or to Corveg factory. You can acquire the pheromones if you decide to kill the queen located in Grayditch sewers ( Those! subquest). If you want to find a positive outcome, you must gain possession of ant queen pheromones. You can talk to Father Clifford and convince him (by lying) that Angela and Diego are sleeping together.
First of all, you can convince Diego that the church should be the most important thing for him and that he should keep ignoring Angela. You can solve this problem trying to achieve a good or a bad ending. Sadly they can't be together, because the boy is an acolyte in Saint Monica's Church. During your first conversation with Angela Staley you'll find out that she's in love with Diego. You can give him psycho if you want to lower your karma. Paulie Cantelli (mentioned by Vera) can usually be found in his quarters in Rivet City - Middle deck. She will also tell you about Lopez trying to commit suicide and about Angela Staley being in love with Diego. You'll find out that Paulie Cantelli is a junkie trying to fight off his drug problem. Talk to her and she can share gossip about her neighbours. Vera Weatherly can be found in Rivet City - Upper deck. If you inform Danvers about an extortion attempt you will help Seagrave and he'll lower his prices. If you share the information with Danvers you will help Bannon and he'll lower his prices. Visit Seagrave's quarters and if you're thorough, you will come across information that ties him to the slavers. Bannon will ask you to find evidence that would implicate Holmes in shady dealings. During your conversation with Bannon you'll find out that Seagrave Holmes is trying to take his place in the city hall. Similar to Megaton, the amount of caps given to him is equal to amount of karma points gained by performing this good deed. You can agree to contribute by giving him bottle caps (max 100 caps at a time). During your initial conversation with him you'll find out that he's running Saint Monica's church in Rivet City. Father Clifford can be found in Rivet City - Bridge, Rivet City - Upper deck or Rivet City - Middle deck. If you're playing as a bad character you can share this knowledge with Sister. In exchange she'll inform about the Temple of the Union.
You can give her 25 bottle caps, so that she can purchase a weapon to defend herself. Talk to Mei and listen to her story about the slavers. She can be found on the top deck of the ship or in Rivet City - Middle deck. The situation here is very similar to Megaton - you can him refined water and in "exchange" you'll raise your karma. You should be able to encounter a beggar named Carlos near the bridge leading to Rivet City.