Jeff is Amy’s boyfriend and the group’s de facto leader, embodying the archetype of the rational leader whose reliance on logic becomes both his strength and limitation. As a pre-med student, his identity is rooted in problem-solving, planning, and control. His actions on the ruins reflect these tendencies, as he organizes the trips, attempts to communicate with the villagers, rations supplies, and develops survival strategies. 

While others cling to the hope that they will soon be rescued, Jeff shocks the group when he suggests collecting their urine, leading the others to feel “sick,” “panic,” and to argue with him (61). He is direct and pragmatic, emphasizing efficiency and survival over emotion. These traits position him as the most capable member of the group, particularly in the early stages of their entrapment, where his leadership provides a sense of order amid chaos.

However, Jeff’s arc reveals the fragility of rationality when confronted with forces beyond his control, emphasizing The Illusion of Control. While he demonstrates adaptability, such as recognizing the vine’s sentience and accepting their intelligence, his belief in his ability to manage the situation gradually unravels. His insistence on control extends into morally ambiguous territory, such as proposing to preserve Amy’s body for food and performing Pablo’s amputation. These decisions highlight his prioritization of survival over ethical considerations, making him a foil to characters like Stacy, who fights against his choices. 

His emotional detachment ultimately contributes to his downfall, most notably in his refusal to check on Amy during the night, which leads to her death. Ultimately, Jeff’s failed escape attempt underscores the limits of his control. Despite his intelligence and preparation, he cannot outmaneuver the forces trapping him.

Mathias is an enigmatic character who frequently embodies stoic resilience. Unlike the four American friends who know each other outside of Mexico, Mathias is a German tourist who meets them out snorkeling, then tags along on their vacation. Initially, his allegiance in the novel is ambiguous. He leads the group to the ruins, providing only a hand-drawn map allegedly from his brother as evidence, while Stacy notes how he is frequently silent and stares at her. These facts, coupled with the fact that he has no point-of-view sections in the novel, introduce the possibility of a human antagonist, which proves to be a red herring, as the only real threat is the vines. He ultimately becomes a key component of the group’s potential for survival, working alongside Jeff to seek out practical solutions while others panic.

Throughout the novel, Mathias demonstrates a pragmatic acceptance of their situation that contrasts with Jeff’s need for control and Amy’s denial. His balanced perspective becomes most clear when he is digging a latrine with Jeff. When Jeff suddenly questions whether there is even a need for something like that, Mathias responds by “shrugging” and saying, “Not really” (160), yet he continues to work alongside Jeff and follow his instructions. At the same time, when Stacy begins to panic about their situation after Pablo’s injury, Mathias instructs her to “be like an animal. Like a dog […] Survive each moment. That’s all” (119), a statement which reflects his belief that survival requires abandoning high-order thinking and focusing on instinct. This perspective allows him to endure the ordeal with a level of composure that others lack. 

His death, accidentally caused by Eric, reinforces the randomness and inevitability of their fate. His representation of a middle ground between rational control and emotional collapse seems practical, yet even he dies in the ruins, highlighting the true strength of the vines.

Eric is Stacy’s boyfriend. He is a dynamic character whose transformation is defined by psychological collapse and bodily horror, making him one of the most disturbing figures in the novel. Initially characterized as impulsive, immature, and somewhat self-indulgent, Eric lacks the discipline and rationality that Jeff attempts to impose. He goes on the hike hungover, avoids responsibility, and relies on others to make decisions for him, positioning him as a weaker member of the group from the outset. However, as the situation worsens, Eric becomes consumed by paranoia, particularly regarding the vines’ presence within his body. This fear drives his actions, leading to increasingly extreme attempts to remove the perceived threat.

Eric’s arc exemplifies the intersection of physical and psychological horror, as his body becomes a site of invasion and loss of control. Most notably, it is unclear whether the vines are actually within his body or not, as he insists he feels them moving, yet Jeff and Mathias argue that it is simply swelling from his injuries. This situation heightens the suspense around the danger, particularly the question of whether the plants are truly capable of burrowing and hiding within his body. His repeated use of the knife to cut himself reflects a desperate attempt to reclaim agency, yet it ultimately accelerates his destruction. 

His inability to distinguish between real and imagined threats highlights the vines’ psychological impact, as they blur the line between internal and external danger. Eric’s psychological devolution also ties into Nature as an Unknowable and Unstoppable Force, as his body becomes the site of a conflict that he cannot win. As Stacy notes, she “couldn’t understand why the vine wasn’t slithering forth to capture Eric, too […] It left Eric be” (312). In this way, his character underscores the idea that there is horror worse than death, as he loses his bodily autonomy and identity before his death occurs.

Amy, Jeff’s girlfriend and fellow medical student, embodies the habit of denial, optimism, and the human tendency to resist harsh reality. Her early characterization emphasizes her emotional intelligence and social awareness, particularly in her relationships with Stacy and Jeff. She provides emotional support for Stacy on the bus, noting how, “[t]hey were best friends, and they were going on an adventure, a hike through the jungle to see the ruins. They held hands and watched the soap opera” (17), with the women feeling comforted by each other. At the same time, however, this optimism causes her to consistently reject the severity of their situation, clinging to the belief that rescue is imminent. This denial serves as both a coping mechanism and a flaw, preventing her from fully engaging with the reality of their circumstances.

Amy’s arc reflects The Illusion of Control in a more passive form than Jeff’s. Rather than attempting to impose control, she denies the need for it altogether, maintaining the belief that external forces will resolve their situation. She argues with Jeff about his plans for survival, insisting that there is still hope that they will be rescued and that he is taking things to the extreme. Her death, caused by the vines silently blocking her airway in the night, occurs without confrontation or resistance. Her death reinforces the idea that ignorance and denial offer no protection against the antagonistic forces at work. Amy’s character ultimately highlights the danger of refusing to acknowledge reality in the face of overwhelming threat.

Pablo is a largely flat and static character, unable to speak English and immediately injured when the group arrives at the ruins. A Greek tourist, he leaves behind his two friends at the resort to join the Americans, unable to understand them or truly understand the point of their trip. His primary role in the narrative is to illustrate the physical consequences of the group’s situation, introducing the friends to the horror of the ruins. 

As an original member of the Greek group that they are expecting to arrive to rescue them, he initially represents external connection and the possibility of rescue, but this role quickly shifts as he becomes incapacitated. His injuries and subsequent suffering reduce him to a passive figure, emphasizing the helplessness of the group as a whole. His eventual death, followed by the vines consuming him, reinforces the inevitability of their fate. In this way, Pablo’s character underscores the body’s vulnerability and the cost of survival in an inescapable environment.