Without telling anyone his plan to get stung by the Grievers, Thomas goes to the Homestead with everyone after dinner and waits for the attack. In the middle of the night, the Grievers come, break into the house, and take a boy named Dave. As they run off, Thomas follows them despite Teresa and Newt’s protestation. When Thomas attacks the Griever holding Dave, the rest of the pack start stinging him with their needles. He knows they’ve stung him when he feels a searing pain. He’s able to fight his away out of the pack of Grievers and then collapses to the ground.
Thomas continues to show his maturity by putting his life at risk to help save the other Gladers. Thomas’ hopefulness also gives him the courage to attack a pack of Grievers head on.
Chuck, Teresa and Newt find Thomas lying in the grass, barely consciousness. They carry him back into the house where they inject him with the Grief Serum. Before he passes out, he whispers that he got stung on purpose.
Thomas will now go through the ultimate test of his maturity: the Changing. If Thomas can get through the Changing without losing his hope (unlike most of the other boys), then he will have symbolically survived the challenges of puberty and adolescence.