Serena was a subject of the Phoenix Project in Salmon Creek. She was best friends with Maya Delaney and Daniel Bianchi, who is also her boyfriend, and is mentioned by both of them throughout the series, though she only appears in The Gathering. Serena was captain of the swim team, and was in the school choir as well. It is revealed that she is a supernatural type called a Xana along with her fellow swim team members Nicole and Hayley, both of whom were friends of hers. She drowns in the Prologue of The Gathering.
The Gathering
Serena is standing on a rock singing when Maya tells her to just jump. She smiles and does an Olympic worthy dive, coming up and teasing Maya that it was her turn. Maya considers Serena the swimmer, as she is captain of the swim team, and doesn't like swimming much herself. The two chat while they wait for Daniel, Serena's boyfriend. Maya thinks about how Serena had made them draw straws last year to see who would ask Daniel to the dance. She didn't feel the same way about Daniel as Serena did so she rigged the game so that Serena won. They had been together ever since. Serena interrupts her thoughts by bringing up Maya's tattoo, or lack of one, they plan a trip to Vancouver next year. Just as Serena is joking about getting her own nightingale tattoo, she is pulled under the water. Maya jumps in to save her, but is pulled under the water herself. When Daniel comes he sees only Maya, as Serena is under the water, and goes to pull her out. Maya tells him that Serena is under and he dives repeatedly to try and find her. The next day the lake is drained and Serena's body is found. The town claims that it was just a cramp that caused her death, but Maya is unconvinced, having felt something pull her down.
A year later, Maya is still not over Serena's death, not able to swim in the lake where she drowned. She thinks about how she could have saved, maybe if she had brought Kenji, or swam harder. She often sits on the edge of the lake, where Serena dived off of, and speaks to her. Maya and Daniel think that a new medicine that Serena was taking before she drowned caused her to have some strange reaction, leading to her death.
The Calling
Serena is only mentioned in this book. After the helicopter crash, Maya is swimming towards land when she is pulled under the water. She remembers what happened to Serena, and whatever is pulling her down now is similar to what kept her from saving Serena. She manages to reach the surface before she drowns.
When Maya and Daniel are sitting in the forest, they talk about how they miss her, and their lives are different a year after her death. Maya assumes that Daniel is not over her as he has not dated since Serena. Daniel finally admits that he dated Serena only because she had asked him to the dance, and it would have felt wrong to say no to a friend. He says that he liked her, but it wasn't going anywhere, that it was only for fun. Daniel confides to Maya that he was never jealous when Serena flirted with summer boys, and that he actually wished she would find somebody she liked, and break up with him. He realized it wasn't fair of him to keep dating her, and stop her from finding someone else. Daniel was going to break up with her.... and then she drowned. He felt awful because everyone made their relationship into something it wasn't. He says that he did miss her, but as a friend, the same way Maya did. Maya thinks about how Serena's last year was good, because she really liked Daniel.
Maya and Sam are discussing her death because Maya assumed that Sam liked Daniel and killed Serena to get to him. Sam assures her that she does not like him that way, and that she was not the one who killed her. The two have a new theory that Nicole was the one who really pulled her under, as Sam claimed she had "a few screws loose when it comes to Daniel".
During Maya's first shift she finds Nicole. Nicole is happy because she assumes that Maya is there to save her. When Maya makes no move to help her Nicole gets angry. She insults Maya and then claims that Serena never worked her for anything. That she only sang in the shower while Nicole practiced endlessly, but Serena was always better.
The Rising
Serena is only mentioned in this book. When at the house that the Nasts had set up for the Project Phoenix subjects, Sam and Maya confront Nicole in front of Hayley and Rafeal. Sam accuses Nicole of killing Serena to get to Daniel. Nicole is stunned and manages to say that she would have had to held her breath for at least 10 minutes and that no one could do that. Maya tells her that Salmon Creek's championship swim team could do it, since they were Xana. She turns to Hayley who confirms that the three girls, Serena, Nicole and herself, all had contests, when the coach wasn't looking, to see how long they could hold their breathes. Both she and Serena could hold their breathes for 5 minutes. Hayley than turns to Nicole and reveals that she was always the winner, staying under the water for nearly 15 minutes one time before Serena freaked out and made her come out. When Nicole still refuses she had anything to do with Serena's death Sam tricks her into thinking that Maya and Daniel were getting together. Nicole has a fit of rage, attacking Maya. As she is dragged away she yells "You think what I did to Serena was bad? Just wait until I get a hold of you!" admitting that she was the one who killed Serena.
When Maya and Rafeal are arguing about how Daniel feels about Maya, it is revealed that Rafe knew they drew straws to see who would ask Daniel to the dance, and that Maya rigged the game so that Serena would win. Serena knew about this and told Daniel when she asked him because she knew he would only go with her if he knew Maya wasn't interested in him. Corey found out from Daniel, and used this against Rafe to get him to back off from Maya in The Gathering.
Appearance
Serena is described as having blond hair, which is a characteristic of the Xana. Maya refers to her, Nicole and Hayley as "blonde and pretty" when trying to determine what supernatural they are.