Brother is a normal person only twice seen in the entire Gone series and is seen to have no powers. His true name is never mentioned.
When Computer Jack was driving away from Coates Academy to get away from Diana he ran into Brother and his sister Emily, who has the ability to teleport her surroundings. Jack was hassled by Emily and Brother until he agreed to repair their Wii. Then the two let him go.
It is unknown what became of Brother or Emily.