Answer
Gordian III was the nephew of Gordian II. Gordian II, along with his son Gordian I, briefly ruled as co-emperors in 238 AD before being defeated and killed by Maximinus Thrax. After Maximinus's death, Gordian III, then a young boy, was proclaimed emperor by the Senate. He ruled under the regency of his father-in-law, Timesitheus, until his assassination in 244 AD.