In the universe of Fallout, there's nothing more frightening than finding out someone's a synth impostor. It's a common theme that's seen throughout the Fallout series, and which is especially explored in Fallout 4 through various quests and even one of its DLCs. Just entering Diamond City alone will reveal to the player how much locals are afraid of synths.

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While some characters are openly synths, such as Nick Valentine and DiMA, others either reveal their true selves when the time is right or fans have discovered their identities later on by finding synth components on their corpses. Sometimes, surprisingly human characters turn out to be complete fakes.

10 Art (The Other One)

Fallout 4 Art Synth Character

One of the many random encounters the player might face is the battle between two identical NPCs. This can happen almost anywhere in the Commonwealth, and sometimes features a random wanderer named Art, who can be seen fighting a copy of himself.

It's impossible to tell with a naked eye whether which one is the real deal. Only by killing the synth can the player find out their true identity by looting the corpse for a synth component. In any case, one of these two is most definitely a fake, and it's up to the player to figure it out.

9 Amelia Stockton

Fallout 4 Amelia Stockton

It's easy to assume that Amelia Stockton is a synth, due to the quest that she's related to. Moreover, players who are part of the Railroad will easily be able to interrogate Old Man Stockton at Bunker Hill about her true identity, but otherwise it's hard to know for certain.

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She's actually a runaway synth, but won't actually know about this herself since she's had her memory wiped. She can be found at the Compound randomly if the player isn't on a quest, and will vehemently keep on denying that she's a fake. There's no fate more cruel than hers, not knowing what she really is.

8 Roger Warwick

Fallout 4 Roger Warwick

Humble farmer Roger Warwick at Warwick homestead doesn't seem like an important character. He's just there, tending to his crops, and the only information given about him is his children stating he's become a kinder man as of recently. That's probably because he's no longer the real Roger Warwick.

The Institute is actually using him for bioscience research, and might even have plans to kill him and his family once the research is finished. However, it's also possible to find out the truth about him when meeting an NPC called Cedric Hopton, tasked with finding someone to assassinate Roger for being an imposter.

7 Mayor McDonough

Fallout 4 Mayor McDonough's Face

Upon first meeting the mayor, the last thing anyone would imagine is that he's actually a synth working directly for the Institute as an agent. It's the eyes and the ears of the Institute in Diamond City, and when he eventually gets caught for his identity, the Sole Survivor can choose his fate.

The sad part about this character is that he's a replacement, an identical copy of the original mayor who was kidnapped and most likely killed. As such, this synthetic version knows it's doing the work of an evil science corporation, rather than being oblivious to its own nature.

6 Shaun

Shaun Fallout 4

The entire main quest of the game centers around chasing after the past. More importantly, it focuses on finding out what happened to little baby Shaun, who, as it turns out, has grown up quite a bit and is being held by the Institute. Well, not quite. As soon as the Sole Survivor enters the Institute for the first time, they're in a surprise.

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Child Shaun is actually a synth, and his true nature is revealed quickly enough by the real Shaun, who now goes by the name of Father. This is one of the most shocking and tragic revelations in the game, one that forces the player to make some extremely difficult decisions.

5 Captain Avery

Fallout 4 Far Harbor Captain Avery

The Far Harbor DLC actually deals quite a bit in synths. In fact, the island is a battlefield of sorts between the local humans, the synth refugees of Acadia, as well as the Children of Atom. No matter what side is taken, the truth about one of the central characters to the DLC will eventually come out.

Captain Avery is the first person to welcome the player into Far Harbor. She's a cornerstone and a leader to the village, but has no idea about her true self until it's actually brought up by the player. She's a replacement without any knowledge of who or what she actually is, which makes her tale even more tragic.

4 Gabriel

Fallout 4 Gabriel In Libertalia

The cool thing about Fallout 4 is the abundance of unique raider leaders that inhabit the various unique locations all around the Commonwealth. Gabriel, the lead raider at the floating city of Libertalia is one of such characters, but as it turns out, he's much more than just that.

During one of the Institute quests, it's revealed he's actually a runaway synth with no memory or knowledge of who or what he actually is. This was all achieved thanks to the help of the Railroad, who gave him a new chance at a normal life. The revelation of his true nature completely shocks his lapdogs when the Sole Survivor arrives to catch him.

3 Paladin Danse

Fallout 4 Paladin Danse

The Brotherhood of Steel is no doubt the last place in the Commonwealth where any undercover synths would be located, right? Well, that's a false assumption. In fact, one of the most prominent characters of the faction and a companion who often goes on and on about evil synths, is a synth himself.

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Paladin Danse's true identity is unknown to himself as well, but once the player arrives into the Institute, they'll uncover some interesting files about his true nature. This launches a new side quest which puts Danse's fate into the player's hands. Although this can't be discovered earlier, there's just something a bit strange about the way Danse speaks in general that might catch the attention of quick-witted players.

2 Magnolia

Fallout 4 Magnolia

One of the major revelations was definitely the true nature of Magnolia, the sultry jazz singer of Goodneighbor's Third Rail. She appears perfectly human, especially since she's talented in her art form and doesn't seem as tense as many regular synths often would.

There's no actual way to find this out without killing her or using some cheats. However, it's definitely true that she's a third generation synth with a highly realistic appearance. It's unclear how she's made it to Goodneighbor, but she was probably given a proper chance at life by the Railroad.

1 Sturges

Sturges Fallout 4

Another highly mysterious and debated case is that of Sturges. At no point during any quests in the game is it revealed that Sturges is a synth. The truth is only found out if the player manages to kill him with console commands despite him being an essential, as he drops a synth component.

It's assumed that he's another one of those synths who has managed to escape, but he definitely doesn't come across as one, nor is this ever talked about in the Minutemen faction quests. And yet, everyone's favorite handyman seems to be more machine than flesh.

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