Chem addict

As the name implies, chem addicts are characters who are addicted to chems.

Fallout 3
There are quite a few addicts in Fallout 3.

Leo Stahl (Megaton)
Talking to the doctor in Megaton can get him to reveal Leo's crazy chem addiction, namely to Jet. After this, the player character can talk to him and talk him into quitting, receiving good Karma). He will give them a key. Go to the Water processing plant, and there is a locked desk full of Jet and money, along with some other chems).

Paulie Cantelli (Rivet City)
Talk to Vera Weatherly and ask her about some gossip. She can tell the player character some interesting information. Mister Lopez is considering suicide, for example. She can also tell them that Paulie Cantelli is addicted to Jet. Asking around confirms this. His room is filled with Jet, Psycho and other chems. It is not free to take and they will lose Karma for doing so. However, the player character can avoid getting caught by simply closing the door behind them. While speaking to him, the player character has the option of offering him Psycho. If they give him enough, he will overdose.

Sierra Petrovita (Girdershade)
Sierra Petrovita in Girdershade is addicted to Nuka-Cola.

Silver (Springvale)
There is a Psycho junkie hiding from Colin Moriarty.

Snowflake (Underworld)
When talking to the ghoul Snowflake, he tells the player character he wants to cut their hair. Then a dialog option is available, "Are you taking Jet over here?" to this, he replies he has nothing else to do but get high. This is strange, considering how Murphy says that Jet has little effect on ghouls.

Zip (Little Lamplight)
Zip in Little Lamplight is another Nuka-Cola addict.

John Bear (The Pitt)
John Bear has a Radaway addiction, along with his brother.

Grudd Bear (The Pitt)
Grudd Bear has a RadAway addiction, along with his brother.

Unnamed addicts
Chem addicts who have gone insane with their chems and are hostile to the player character can be found predominately around the El Rey Motel. One is found in one of the rooms on the second level of the motel. The others in the El Rey are dead, lying on the floor.

Three non-hostile chem addicts are found at a campfire just south of Fields' shack across the railroad tracks.

Bill Ronte (Freeside)
Bill Ronte used to manage and maintain the Freeside water pump, but then became addicted to Dixon's whiskey.

Jacob Hoff (Freeside)
Jacob Hoff ironically brewed detox chems before he worked for the Garrets. He has become addicted to Dixon's Jet.

Pacer (King's School of Impersonation)
Member of the Kings who has a Jet addiction and a weak heart - a deadly combination. He can be killed by putting Psycho under his mattress with his stash of Jet.

Fiends
All Fiends, with a few exceptions, are considered crazed druggies and are often in possession of lots of Psycho, Jet and Med-X.

Ricky (Northern Passage)
A Psycho addict and a compulsive liar hired by the Happy Trails Caravan Company for an expedition into Zion Canyon.

Mobius (Forbidden Zone Dome Entrance)
Resides in the Think tank and has a Mentats addiction.

Mama Murphy (Museum of Freedom)
A Jet, Mentats and Psycho addict. She is a fortune teller that can reveal some parts of the Sole Survivor's future using the Sight, her name for chem-induced hallucinations.

Hancock (Goodneighbor)
A Mentats addict, using them to become smarter. A companion in Fallout 4, as well as the Mayor of Goodneighbor.

Henry Cooke (Colonial Taphouse)
A Jet, Mentats, Psycho and Buffout addict. He is the owner of the Colonial Taphouse and is involved in a relationship with Darcy Pembroke. He is also an informant for the Institute and a chem dealer.

Cait (Combat Zone)
A Psycho addict who was sold into slavery by abusive parents. She arrived to the Commonwealth, and was hired by Tommy Lonegan to fight in the Combat Zone. She is also a potential companion with a quest to get her off of Psycho.

Patrick (Drumlin Diner)
A Jet addict, he is the son of Trudy and is struggling to pay his dealer, a raider known as Wolfgang.

Bobby De Luca (Vault 81)
A Jet addict whose sister, Tina De Luca, supplies him. His addiction to Jet is also what indirectly causes Austin Engill to come down with the mole rat disease. The Sole Survivor can sell Jet to Bobby for 75 caps a piece. If they keep selling to him, he may be found dead in his room.

Unnamed addict (Landview Lighthouse)
A chem addict that died near the picnic area directly north of the Landview Lighthouse left a holotape, Where am I?, describing an unsettling encounter with a land-locked lighthouse.

Clara's mother
Clara's mother was addicted to Nuka-Cola, as described in Clara's note to mom.

Sam Blackwell
Sam Blackwell had a dependency upon Mentats.

Rose
Despite being a robot, Rose has an addiction to various chems. In the cut quest, Feed the Habit, she asks the player character to obtain chems for her.

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