Aiden Caldwell

Family Mia (adopted sister) † dead Vincent Waltz (adopted father) † dead Parents' names are not mentioned †

Status Alive (human-bat hybrid) human Physical description of the human Hair dark brown Eyes blue

Aiden's exact date and place of birth is unknown, but it's likely that he was born either in the year 2013 or 2016 either before or during the Harran Virus pandemic that eventually spread across the world. His father saved his life when he was young, telling him never to forget who he was or where he came from. He is an infected survivor in an infected world, where getting attached to others is deadly.

He is a member of an outcast group known as the Pilgrims, a group that wander the world and are compared to Japanese Ronin and Old West desperadoes. He claims to have travelled over 2,000 kilometres (1,242 miles) from Crossdale River.Aiden's travels lead him to the City in search of his lost sister, Mia. The only person he remembers from his past, who he believes is the key to unlocking it and teaching him who he really is.

After escaping a group of virals in a tunnel, Aiden meets a fellow pilgrim named Spike. The two of them walk through the forest to a mansion where they drink beer and Spike tells him that he got a trail on a guy named Waltz, telling him to contact an informant at a nearby house. After securing a safe zone in the house, Aiden sleeps and has a dream where he and his missing sister Mia are in a hospital being experimented on, a fire starts and Aiden loses track of Mia.

The morning after, Aiden contacts the informant and the two plan to meet in the sewers, Aiden asks the informant if Mia is alive and the informant confirms she is alive. Aiden makes his way to the sewer and encounters a volatile, who bites his hand, the informant saves Aiden but Aiden has a seizure and passes out.Aiden wakes up to the sound of the informant being interrogated by a group of bandits, when he goes to investigate he is attacked by bandits and kills them, after a few fights the informant gives Aiden a GRE Access Key telling him to go to Fisheye and find Lawan. The informant locks Aiden in a vent as Waltz comes into the room and kills the informant, Aiden has a seizure and Waltz notices him and sends his men after him. After escaping Waltz and his men, Aiden finds an entrance into Villedor.

Aiden finds himself in the Bazaar, home of one of the largest factions in the city, the occupants quickly learn he is without a biomarker and also infected and try to hang him to prevent an attack, Aiden is saved by a man named Hakon at the last second and is taken back to a workshop owned by Sarah and Jana where Hakon injects him with an inhibitor. despite the injection, Aiden tries to attack Sarah but is knocked unconscious by Jana. Aiden wakes up and Hakon tells him he needs a biomarker to get to the Fisheye, the two leave before nightfall and stumble upon a military crate that Hakon was after, Aiden uses the GRE Access Key to open a lock much to Hakon's surprise. Before they can talk about it, night falls and Aiden has a seizure but is saved by Hakon, the two run to the Bazaar but are turned away by the gatekeeper due to Aiden not having a biomarker. A howler spots them and they run to Cillian's Hideout. At Cillian's hideout, Hakon and Cillian argue before Hakon goes to scout out Saint Joseph's Hospital while Aiden sleeps, he hears Mia taunting him in his sleep before Hakon calls him on the radio telling him to meet him in Saint Joseph's Hospital. In the hospital Aiden and Hakon sneak by infected and at one point the two are separated when an elevator crashes, Aiden finds an inhibitor and injects it so he can climb up to Hakon.

After meeting up with Hakon, he gives Aiden a biomarker but his biomarker starts going off due to low immunity and Aiden has to quickly escape. After escaping Hakon asks him about what he will do when he finds his sister, and Hakon tells him he wants to live by the ocean and asks Aiden for help. Hakon gives Aiden a pair of Binoculars and tells him to head for the Bazaar. When Aiden arrives at the Bazaar he helps out the locals while he waits for Hakon to give him a call.

After leaving Villedor, Aiden and Spike attempted to break out Kyle Crane, but failed due to being overwhelmed by The Baron's guards, allowing only Crane to escape. While in captivity, Aiden was experimented on due to being a Infected hybrid.

Sheriff notices The Baron's men bringing lots of equipment and men into a salt mine. Crane and Sheriff go inside to investigate, but this was a setup from as the Sheriff was forced to either die or help The Baron capture Crane. Aiden is let out of a cage and escapes up a wall.

In a last stitch effort to draw The Baron out of his palace, Crane and his allies lure and capture The Beast using a gas canister on a truck to trap him in a cave. Crane and Lydia successfully subdue him and bring him to the Cave. Using Crane's blood plasma, they are able to revert The Baron's effects and make him human again.

As a survivor of the post-Fall world, and partly due to the tests ran on him as a child, Aiden is an exceptional survivor, his strength, speed, and affinity for combat make him a strong survivor, capable of performing feats that no one else has, and regularly pushes through dungeons and death-traps that no other had dared to touch. His skillset being compared to the likes of Kyle Crane, a survivor of the 2015 Harran pandemic who became known as the 'Legend of Harran' due to his extensive skillset and physical capabilities as a Nightrunner.

Throughout the game, it's revealed that Aiden had been experimented on during his childhood by Waltz, these experiments had chances of causing blackouts, in which Aiden would mindlessly attack those around him, his strength and speed were bolstered during these events, capable of tearing apart Volatiles with his bare hands. Aiden learned to gain control of it during his confrontations with Waltz, going from blacking out and losing control to being in complete control in his final fight with Waltz.

Aiden can additionally enhance his physical capabilities with the use of Inhibitors, drugs created by the GRE to enhance the user's strength and immunity to THV.

Aiden's unique skillset gives him the power to become an agent of change within the decaying metropolis of humanity's last stronghold, Villedor.

Aiden is a young Caucasian male in his early 20s, with short brown hair and blue eyes. His face is weary and slightly scarred. He is of average height, with an athletic physique.

Aiden is portrayed with a younger looking face, devoid of stress and scars in the cover art, though the artwork only uses a side shot of his face.

During the E3 2018 world premiere, Aiden initially wears a dark green long sleeve shirt, rolled up to the elbows, dirty khaki and light brown pants, and brown boots.

In Promotional advertisements and game updates, his main outfit is the Stay Human outfit, consisting of a white, blue and red face mask, a worn denim jacket with a red hood, with red trim around the waist and arms, a plain white T-shirt with a blue and turquoise print, worn charcoal running pants with a dual stripe print on the left leg above the knee, dark green shin guards with a small lime line running down towards the foot, with white, grey, and red sneakers. His starting outfit is a modified version of the Pilgrim's outfit, lacking the hood and face mask.

Aiden is friendly and usually amicable to most survivors he comes across, willing to help them out if they need it. He's sympathetic and introspective, capable of seeing the bigger picture depending on the scenario, evident during his conversations with Thalia in the Book Club quests, depending on the dialogue options. Despite his willingness to help and putting his own goals aside for the sake of others when they need it, Aiden is an opportunist, only helping others throughout the story if they can help him, and can become easily angered when a promise made to him is either broken or pushed to the side. This anger is evident during his quest to get to the Central Loop, when either Aitor or Sophie delay giving him access to the Metro Station.

As a Pilgrim, not being tied to any side or faction, Aiden makes it clear that he has no stakes in the conflict between the Survivors and the Peacekeepers and will only care for either side if they can help him with his own goals, evident when Sophie tries to ask for his help in the conflict, Aiden bluntly tells her that he doesn't care about the fates of either side.