Thomas, the main character, is a young boy. He's immune to the disease that eradicates humanity called 'The Flare'. His family died after they brought him to the WICKED base because outside the institution are many people suffering from the Flare. The Flare is a contagious disease and it slowly affects your brain and you become kind of a zombie, a crank. Before his parents brought him to the institution, he lived in a little house in the forest. Thomas is around 10 years old in the beginning of the book but at the end he's around 17 years old.
He is very curious, smart and not scared to do things that are not allowed. All the tests he has to do are meant to find the difference between his brain and the brain of a normal person who isn't immune so the scientists can find a cure. He is not selfish at all because everything he does has to do with finding a cure to the Flare so they can save humanity. Sometimes he is a little bit stubborn when he does other things than he were asked to do. His dream is to find a cure so his life can be normal again but he didn't know that the whole world has been burned down because of the heat from the sun. His life will never be the same as it were before. After the doctors told him that the world is in catastrophe he is still positive and keeps doing tests to find a cure. Overall Thomas is a curious and positive person who always tries to find a solution.