|Eli Vance (father)|
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. Mossman because of Mossman's somewhat patronizing attitude towards her, as well as Mossman's interest in her father. At the end of Half-Life 2, this hostility has seemingly vanished, when Dr. Mossman helps to free Alyx and her father from the clutches of Dr. Breen.
Though Alyx was only a child when Gordon was employed at Black Mesa, Gordon'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 Gordon 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 saying "Dad" in an embarrassed tone. Continuing this theme, Episode One contains many situations where this relationship is developed. Alyx hugs Gordon when her robot, Dog, finds him (and becomes clearly embarrassed afterwards), and at one point she jokingly asks Gordon if there is room for two in Gordon's H.E.V. suit. Barney Calhoun additionally blurts out "Go on, she's waiting for you. You lucky dog, you!". 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. During the middle segment of the game, when Gordon and Alyx drive across country in a modified vehicle, Alyx can be seen winking at the player. Finally, the Vortigaunts' notably "weave the Freeman's life with hers," while reviving and healing Alyx, thus explicitly connecting the two characters' wellbeings. 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.
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 her witnessing her father's gruesome death remains to be seen in Episode 3.