- "He's like a lion in a cage."
- —A young Jodie, describing Aiden's presence
Aiden (stillborn May 10, 1990) is the secondary playable character, and the deuteragonist of Beyond: Two Souls.
Aiden is an Entity that has been linked to Jodie Holmes since birth. They are connected by an ethereal tether, that can be seen when switching to Aiden's view. This tether acts as a spiritual link between Jodie and Aiden that keeps Aiden bound to Jodie. Though he can go farther away from Jodie in some situations, the separation causes Jodie excessive amounts of pain and lasting disorientation. Throughout the game, Aiden shows that he is capable of human emotion through his interactions with Jodie and his own frustration at the restraining tether.
Jodie is the only one capable of listening to or communicating with Aiden. Cole and Ryan can also communicate with Aiden when Jodie is being sedated by the CIA. However, whether she is able to control Aiden against his will is up for debate. While she often instructs Aiden in various tasks throughout the game, he usually does so willingly. Jodie does force Aiden to open up her apartment door for her in "The Dinner" when he tries to lock her out, but it required some discomfort, and gave her a nosebleed. He tries to stop her when he disagrees with her, not by directly hurting her, but by making obstacles for her. It is unknown what Aiden's main goal in the game is, although he appears to think of Jodie as his charge. Still, since he is bound to Jodie, his sole purpose in life(in his case, Jodie's life) is to protect Jodie from whatever danger.
Jodie and Aiden seem to age in sync, for as Jodie grows older, Aiden grows stronger, and their bond grows greater. The powers displayed by Aiden include a powerful psychokinetic thrust and shock that can move physical objects and damage spiritual entities, basic possession skills that allow him to take over the minds of nearby humans, a Vaderian "force choke" that he uses to strangle various hostiles, psychic abilities that allow him to direct mnemonic imprints from certain spots to Jodie for her to experience, and the ability to "read" the souls of recently dead human beings, the technical term being mediumship. He can also heal Jodie and the people who Jodie directs him to heal by greatly speeding up the healing process and relieving the pain, but the only healing notably done was wound-healing and cold-relieving(relieving Jimmy's shivering, possibly due to drugs). He is also capable of creating a protective field, which can shield Jodie from harm like bullets and fires, also used to breaks Jodie's fall exponentially. Aiden creates the field only on Jodie, but still capable of protecting other people, like Salim and Tuesday.
As the story advances it is revealed that Aiden is Jodie's stillborn twin brother. Jodie was delivered safely from her mother's womb, but her brother was strangled by the umbilical cord. Rather than passing on, his soul became linked to Jodie and remained that way, growing up as if it occupied a physical body.
The man Aiden would have been was shown briefly after Jodie shut down the Black Sun; however, his facial appearance was obscured. After the events of Black Sun, Aiden was separated from Jodie, causing a massive memory lapse in Jodie that spurred her to write about her experiences in a personal journal. It seems that Aiden is linked not only to Jodie's active mind, but also to her memories, which might explain why his behavior matched Jodie's so often as if they were shaped by the same experiences. Eventually, Aiden returns to Jodie, but as an entity separate and unbound.
In the final mission, Aiden gets ripped out of Jodie and gets stuck in the infra-world. Even though Aiden's soul is free, he returns and watches over Jodie, as seen in the very last scene of each ending in the game (unless you choose to live with Zoey), where the writing: "Still here" appears in front of Jodie.
- The name "Aiden" comes from the word "aed" which means "fiery, little fire" in Gaelic. 
- Aiden is pronounced 'EYE-den' as opposed to 'AY-den'.
- Aiden can only possess humans as long as he remains untouched by another human; this can be seen in chapters such as Like Other Girls. Being touched by another person will cause the person's soul to reject Aiden and he will either need to find a different approach or repossess the person to accomplish the task required.
- In the chapter Like Other Girls, Nathan can say his name incorrectly if Jodie is caught before she and Cole leave the parking lot, if Jodie took revenge on the teens in The Party and when Jodie is about to leave for the CIA , Nathan will say it incorrectly again. (Determinate)
- Jodie can also mispronounce his name in the chapter Dragon's Hideout.
- In the chapter Navajo, though it is very faint, Aiden will say goodnight to Jodie on the first night.