In the time before the beginning of the series, originally out of pity, Aidan saves Josh from being tormented by Marcus and before the two became good friends with Aidan getting Josh a job as an orderly at Boston's Suffolk County Hospital, where Aidan has been working as a nurse.
The two later become room mates with a mutual intent to fit back into society.
After Heggeman leaves to tell the other vampire clans of Bishop's planned coup, Aidan honors Rebecca's wish to die rather than live as a vampire.
Several days later, Aidan is reunited with an elderly Celine, learning she came to Boston to live with her daughter while she receives treatment for lung cancer, even though she does not plan on living through the treatment.
After Heggeman crowns him as the new head of the Boston vampires, Aiden learns that Mother wants to meet with him over the matter of Bishop's orphaned vampires.
When Aidan suggests the orphans can be reformed, Mother decides that the orphans should all be culled and that Aidan will not lead Boston, but instead assist her daughter Suren in taking over with his freedom from vampire society as a reward.
Reluctantly, Aidan drains Celine of her blood, killing her, but allowing him to heal completely.
Expecting that Josh would attempt to fight for him, Aidan has Sally trap Josh in the hospital basement while he decapitates Bishop in their fight to the death.
Aidan approaches Henry to gather all of the orphans at the house of a man who sells passage through the threshold so he may save the orphans and reintegrate Henry into vampire society.Rebecca later acts on Bishop's order to sway Aidan's thoughts on her by sending him a DVD where she has sex with a man before draining him dry of blood.Though he promises Josh and Sally that he will get rid of the DVD, Aidan secretly keeps it.As his first task for Suren, Aiden is told to turn Cecilia, a cop she has met, to serve as their new police liaison.Aidan refuses, knowing he will bleed Cecilia dry, and ends up at a bar where he meets Julia, a new doctor hired by Suffolk County Hospital, and begins an intimate relationship with her.He is a quiet, calm, soft-spoken, and somewhat jaded vampire who is 257 years old, having been sired by Bishop during the American Revolution.