Alyx is the daughter of Dr. Eli Vance. Her mother, named Azian, can be seen in a family photograph in Black Mesa East (the photograph appears again in Episode Two at the White Forest facility). Alyx's character uses a modified version of real-life actress Jamil Mullen's face, and her voice is performed by Merle Dandridge. Azian lived in the facility's dormitories with Alyx, but died during the Black Mesa incident. In Episode Two, it was revealed that Alyx would have died at Black Mesa as well, except that the G-Man saved her "for his own purposes" and gave her back to Eli.
Alyx is a skilled hacker adept at infiltrating Combine computer systems and reprogramming them. If hacking is not possible, she possesses a multitool that uses an electric charge in order to bypass security systems, open locked doors, and re-program rollermines and automated turrets to attack humanoid and alien enemies. She is also very proficient with an automatic pistol, a shotgun, a sniper rifle, and in unarmed combat. She fights alongside Gordon Freeman briefly during both the Entanglement and Anticitizen One chapters of Half-Life 2. In Episode One and Episode Two, Alyx accompanies the player for most of the game and demonstrates fighting skills previously unseen, such as kicking a headcrab zombie in a fight.
Despite Alyx's "friendly nature", she shows some hostility towards Dr. Judith Mossman due to her somewhat patronizing attitude, as well as Mossman's apparent interest in her father. The hostility abates at the end of Half-Life 2, when Dr. Mossman helps Alyx in escaping the Citadel. She also holds Breen responsible for her mother's death (when she was captured, Breen tried to threaten Eli with Alyx' life by saying "Do you let your stubbornness doom our entire race, or...[places his hand on Alyx' face] would you give your child the chance her mother never had?" Alyx responded by spitting in Breen's face and said "How dare you even mention her?!").
Alyx also has a good sense of humor evidenced by the jokes she makes about the Combine or Gordon's silence. An example of this can be seen in the Lowlife chapter of Episode One, when she begins to make noises like a zombie to scare the player. Upon being found out, she says "haha, gotcha." After the player destroys the auto-gun in the scrapyard in the Under the Radar chapter of Episode Two, Alyx can sometimes (depending on the player's actions) be heard calling out "Hey, boyfriend!" to get Gordon's attention (this is an apparent reference to earlier in the chapter when an NPC can be overheard asking Alyx if Gordon is her boyfriend). Whether this sense of humor survives the events of Episode Two remains to be seen in Episode Three.
Though Alyx was only a child when Freeman was employed at Black Mesa, Freeman's stasis between the events of Half-Life and Half-Life 2 has effectively erased any appreciable age gap between the two characters. Thus, sexual tension begins to arise between Alyx and Freeman during the course of their travels together. It is first witnessed during the chapter Black Mesa East, when her father tells her, "There is nothing Gordon can't handle…with the possible exception of you". She replies by embarrassedly muttering "Dad, please..."
Continuing this theme, Episode One contains many situations where this relationship is developed. Alyx hugs Gordon when her robot, Dog, finds him, and at one point she jokingly asks him if there is room for two in his HEV suit. Barney Calhoun additionally mentions that Freeman is a "lucky dog" to travel alongside Alyx.
In Episode Two, when the characters reach the White Forest facility, Eli mentions that, with the reproductive suppression field turned off, Alyx and Gordon should "do their part" for the revival of the species, to which Alyx responds with an embarrassed chuckle. He replies that she can't blame him for wanting grandchildren. During the middle segment of the game, when Gordon and Alyx drive across country in a modified vehicle, Alyx can be seen winking at Gordon. Finally, and perhaps most notably, the Vortigaunts "Weave the Freeman's life with hers," while reviving and healing Alyx, thus explicitly connecting the respective well-being of the two characters.
The game commentary that is given during the "elevator scene," in which Gordon waits for the elevator that takes him down to the core, verifies that such a relationship was intended.
In Black Mesa East, Alyx argues heatedly with Dr. Judith Mossman. Alyx's hostility towards Mossman is seemingly justified: Gordon and Alyx learn in Entanglement that Mossman has betrayed the resistance and given away the location of their hidden facility. Nevertheless, in Dark Energy, Dr. Mossman explains her actions and the two women finally make peace.
In the ending scene of Half-Life 2, Alyx is with Gordon at the time of the dark energy explosion.
In Episode Two Alyx finds Gordon in the wrecked train shortly after awakening and helps him out using the Gravity Gun to remove the door. She and Gordon travel to the White Forest Rocket Facility to deliver a crucial information packet stolen from the Citadel. She is later gravely wounded by a Combine Hunter and put into a coma. She is saved by a vortigaunt and taken to the underground mines to be healed. Gordon and this vortigaunt travel deeper to retrieve an Antlion "Larval Extract" needed to save Alyx. During a surreal "heart-to-heart" between Gordon Freeman and the mysterious G-Man, Alyx is programmed to tell her father to "prepare for unforeseen consequences". Afterward Alyx awakens and travels with Gordon to White Forest, battling Combine soldiers, Hunters, zombies, a Hunter-Chopper, and have an encounter with a Combine advisor which later flees away to safety.
They finally arrive at White Forest, where she meets up with her father; who slyly hints that he wishes Alyx and Gordon to have children together. She delivers the Combine data to Dr. Kleiner, who manages to decrypt it and discover that Judith Mossman has found the legendary Borealis. During a heated discussion between Kleiner and Eli Vance, she stares at the screen when the G-Man's image flickers and her programming is activated, leading her to transmit her father the message; she clearly retains no memory of it afterwards, proving that the G-Man's influence is far greater than believed. Later on, while Freeman is defending White Forest, she fixes up an old helicopter, a vintage Vietnam People's Air Force Mi-8 and gets it working again while Gordon defeats the incoming Striders trying to destroy the silo.
After Kleiner and Magnusson successfully disable the Combine superportal, Alyx and Gordon head on to board the helicopter to search for Mossman at the Borealis Science Vessel when they are attacked by two Advisors which break into the hangar. Struggling to free themselves from the Advisor's telekinesis, they watch helplessly as Alyx's father is killed and fed upon. Dog then jumps down from the roof and viciously attacks one of the Advisors, wounding one and causing them to flee, saving Alyx and Gordon. Alyx cries, embracing her father's corpse whimpering "Don't leave me." The screen then fades to black and the credits roll.
weapon_alyxgun). Originally, it was intended to be an assault rifle, submachine gun and a pistol in one, becoming a given weapon by extending its body and barrel, and forward grip. This feature was scrapped before release, though. This gun is not available to Freeman, although the player can obtain it via the developer console. Certain aspects of this weapon can be found in user recreational modifications from Half Life 2 such as "Gmod" & "HL2: Capture the flag"
Late in Episode One, Alyx grabs a shotgun (identical to the one available to the player, which resembles a Franchi SPAS-12) and wields it throughout the hospital in Chapter 4. At one point, she also uses an Overwatch sniper rifle, although like Combine snipers she is not actually seen when using the rifle. Twice in the game she uses mounted Combine machine guns to provide cover fire for Gordon.
Early on in Episode Two Alyx once again uses an Overwatch sniper rifle to provide covering fire for Gordon as he retrieves the car. Originally, Alyx was to act as a gunner with a mounted gun from the passenger's seat in the car, but this idea was scrapped before release, and instead she fires her regular gun during periods where the car is moving slowly enough for her to have a clean shot.