A

A is a 16-year-old being that is transferred from one person's body to another based on proximity and similar age. They are forcibly ripped from that body at midnight and they wake up in the next when the morning comes. They have no recollection of when it started or whether it's been happening their whole life.

Early Life
Throughout the duration of the series, scattered fragments of A’s childhood life have been briefly mentioned.

Rhiannon
Rhiannon is A’s girlfriend. The two have broken up once throughout the duration of the story but eventually got back together. Before the two got into a relationship, Rhiannon was in a relationship with Justin, but they broke up after he caught the two hugging and assumed that Rhiannon was cheating on him.

Nathan Daldry
A occupied Nathan’s body for a day, but was not cautious with his actions, leaving Nathan with a few memory of what happened during the day and also getting him involved with the police and media, as well as Anderson Poole, whose body was occupied by X during that time. Eventually, A answers all of Nathan’s questions, and Nathan soon gets caught up with A’s troubles along with Rhiannon.

X
X moves from body to body like A, and the two build a solid relationship until he is forced out of Wyatt Giddings’ body and killed in the process.