Major Story Arcs
Jonah joins the Grendel forces in order to support his poor family, under his wife's protests. However, he soon finds that being a Grendel is a terrible experience. He is put in a clan under Balaam, a cruel taskmaster. They brand Jonah's face, beat him, and brain wash him. One day when a fellow Grendel tries to sexually molest Jonah, Balaam kills the other Grendel. This event finally leads Jonah to psychologically break and to become one of Balaam's most fervent followers.
He and his fellow clan members engage in wholesale slaughter of whole towns, for no apparent reason; it is unclear whether they are really following the government's orders or acting on their own. Balaam heavily doses his Grendels with the drug Primacin, which helps them lose all touch with their feelings and humanity. Jonah kills his best friend because he is too badly wounded. Their clan comes upon a town and begins to kill everyone, when Jonah finds a mother and child that looks sort of familiar. He slowly begins to realize that it's his own family, and isn't sure what to do, but Balaam forces him to kill them. Jonah loses his mind and becomes amnesiac, unable to cope with what he has done. He wants to die, but now finds that he is unable to.
He wanders around and finds himself upon a pirate ship, which tosses him overboard on a raft, which eventually lands in Antarctica. He survives the cold even without any winter clothing, and when a pack of dogs tries to eat him, he is wounded but essentially unharmed.
He is rescued by Caroline Konard, the leader of a team of scientists at Ice Station Hellman that are tasked with overseeing a toxic waste dump. However, UNOW, the world's government, stops communication with the team and they begin to wonder whether they are being left to die.
Just after she brings him back to the base, the scientists start to die from a strange condition in which they quickly go mad, start bleeding from their eyes, and then burst from the inside out in an explosion of blood. Some of the scientists, led by Drake, believe that the disease is an infection and that Jonah is the host, and plot against him.
Caroline, whose late husband was a Grendel, feels sympathy toward the Grendel and argues that there's no evidence that leads to the idea that Jonah is responsible for the scientists' lethal condition. She begins to fall in love with him.
An earthquake ravages the base. Jonah is trapped under some debris, but once again survives unharmed. Caroline tries to figure out what caused it, while dealing with increasingly mutinous challenges from Drake and more bloodily-dead scientists. Alexander, an old, overweight ex-Grendel, is her only ally besides Jonah. They eventually discover the earthquakes are being caused by a giant monster that is moving around underneath the ice. Jonah sets off some bombs to bury the monster, and saves Drake from death, but Drake's feelings toward him don't change.
Drake's team of scientists captures and crucifies Jonah and leaves him to die, but once again is essentially unharmed by the experience. Alexander finds him, and they bond; Alexander is also an ex-Grendel running from his past. Alexander and Caroline secretly bring him back to the base, which Drake now controls.
They figure out that the scientists are dying from exposure to the toxic waste, not a virus from Jonah, but Drake won't listen. Caroline destroys the dump, but the explosion frees the monster, and it attacks the base. Jonah goes off to fight the monster. Drake falls prey to the toxic waste condition and goes mad, attacking Caroline. Alexander saves her, and she manages to shoot Drake--but he kills Alexander first.
Outside, Jonah tries to lead the monster away, but it doesn't work. As he fights it, he finally remembers what he did to his family. In final desperation, he jumps inside the monster's mouth so that it swallows him, and Jonah sets off his last bomb. The bomb explodes the monster's chest, and it falls on the base. Jonah is again unhurt, and searches the wreckage, but everyone inside is dead. He lays down in the snow, still unable to die.
Powers and Abilities
Jonah is a trained warrior, veteran of many campaigns to kill entire towns.
After killing his family, he finds himself unable to die. He doesn't have a healing factor; he can be wounded, but those wounds don't seem to cause him pain or stop him from functioning. Some of the things he survived include extremely cold temperatures, being eaten by dogs, having a building collapse on him, and the enormous explosion that easily killed the several-story-tall monster that had already eaten Jonah.
This ability seems to be supernatural, and based perhaps on his connection to the Grendel spirit in some way.