The 5th Wave book series revealed who Cassie Sullivan ended up with, but it's not who you think. Rick Yancey's sci-fi trilogy of novels explores an alien invasion that came in five waves through the eyes of a teenager. At the center of the story is Cassie, a social outcast who never thought she would be swept up in a fight against alien invaders after losing her parents during the first four waves.
The first four waves include an electromagnetic pulse that rendered cars and digital devices unusable, natural disasters like tsunamis and earthquakes, a rare case of Avian flu that killed most of humanity, and the emergence of sleeper agents known as Silencers.
After the death of her parents, Cassie took an oath to protect her little brother, Sam, but they were separated due to the arrival of Silencers posing as members of the U.S. Military in the camp where they settled in. Being separated from Sammy became the turning point, so she could eventually meet Evan Walker.
J Blakeson's live-action movie The 5th Wave, from 2016, delivered a similar introduction for Cassie, who was portrayed by award-winning actress Chloë Grace Moretz.
So Do Cassie and Evan End Up Together After The 5th Wave in The Infinite Sea / The Last Star?
Cassie met Evan under the most dire circumstances after she was shot by an unknown Other while on her way to Camp Haven to save her brother, Sam. Cassie was hesitant to trust a stranger like Evan, considering she saw firsthand how the invaders (posing as the military) brutally killed all the adults (including her father) in their camp.
However, Evan proved that he is a friend by nursing Cassie back to health, and he even agreed to join her in her quest to save Sam in Camp Haven and destroy the compound. Despite that, Evan is hiding a sinister secret because he was actually a Silencer, a sleeper agent tasked with eliminating human survivors to uphold the invaders' mission.
Although he was slated to be a Silencer, saving Cassie from certain doom reawakened his humanity. He chose to align with Cassie's mission and the survivors to help them overcome the Others' quest for supremacy on Earth.
During their journey to Camp Haven in The 5th Wave, Evan and Cassie shared a kiss, cementing their love for one another. Unfortunately, after they kissed, raiders in the form of other Silencers attacked their hideout, forcing Evan to reveal to Cassie who he truly is.
After the revelation, Cassie became hesitant to trust Evan again, but he proved that he was on her side by successfully infiltrating Camp Haven and detonating several bombs to destroy it. While Evan's fate was left ambiguous at the end of The 5th Wave, the second book, The Infinite Sea, confirmed that he was still alive, though Cassie and Evan didn't end up together after she thought that he died in the explosion.
As a result, Cassie turned her attention to her high school crush, Ben Thomas Parish, who served as the leader of Squad 53 (the squad responsible for Camp Haven's downfall), after they reunited during the rescue mission for Sam. The pair's friendship, though, didn't turn into something more since Cassie was still hung up on Evan.
Meanwhile, Evan was still in recovery after he was found by his friend and fellow Silencer, Grace, after the explosion. After rejecting Grace's advances toward him, Evan was determined to find Cassie and help her continue her mission of defeating the invaders.
Grace was hellbent on pursuing Evan as her lover, which allowed her to track him down and Squad 53, leading to an all-out clash in their hideout. Evan once again proved his loyalty to humans and Cassie by helping them defeat Grace.
The third and final book, The Last Star, showed Cassie as a full-fledged leader of Squad 53 alongside Ben, with Evan as their strong and highly-skilled enforcer. While Cassie did have lingering feelings for Ben, it was made clear that Cassie had genuine love for Evan, especially after he proved himself to her several times.
Unfortunately, Evan and Cassie don't end up together in The Last Star because she makes the ultimate sacrifice by taking an explosive pill while inside the Mothership, which causes it to explode and finally be defeated. Cassie's sacrifice was both heartbreaking and totally understandable because she knew, at that moment, that it was the only way for humanity to turn the tide and win a major part of the battle.
While she didn't end up with Evan or Ben in the end, many believed that Cassie would be at peace with her sacrifice because she did it to preserve humanity and become a beacon of hope for those who survived.
The True Meaning of Cassie's Sacrifice in The Last Star
Cassie's death in the mothership explosion meant that she fulfilled her mission of saving humanity and preserving what's left of them amid the turmoil caused by the invasion. By doing so, she ultimately stopped the 5th wave, but at the cost of her life.
It was unfortunate, but Cassie had been on this trajectory since losing her parents in the first book. While she made it her life's mission to protect Sam by whatever means necessary, she knew that he would be in a good place, considering he had already forged a strong bond with Ben and the rest of Squad 53.
As for Evan, there was a sense that Cassie knew they would never work romantically because there was always a side of her that would not accept his heritage of being The Other (despite proving countless times that he was on her side). Still, there was no denying that Cassie still loved Evan, and her sacrifice inspired him to carry on and continue her legacy by helping Earth in its rebirth and eliminating potential strays of the Others that the explosion did not kill.
