Marcus Aurelius Numerianus was the younger son of the Emperor Carus, and brother to the future Co Emperor Carinus. Numerianus was proclaimed Caesar soon after his father's accension to power in AD 282. Numerianus, like his elder brother Carinus, took the titles nobilissimus Caesar and princeps iuventutis. Although equal in title he was the junior of the two Caesars. His brother Carinus held an ordinary consulship in 283 with his father and was promoted to the rank of Augustus; Numerianus remained with his father in the junior office.
In order to further bolster his new dynasty, Carus arranged a marriage between Numerianus and a daughter of the Praetorian Prefect Flavius Aper. When Carus left for Persia early in 283, he took both his son Numerianus and the Preatorian Prefect Flavius Aper with him. Later in the year Carus died suddenly, and it may have been Flavius Aper who arranged the acclamation of Numerianus as Augustus. The legend said that Numerianus was elevated to the imperial purple by the legions after the death of his father Carus by a bolt of lightning. The army, superstitious and fearful of the wrath of the gods after the lightning stroke, insisted that Numerianus abandon the victorious Persian campaign and lead them home. They were so unsettled by the freakish event that they willingly abandoned all prospects of sacking and plundering Persian cities.
Numerianus had the task of leading the army back from Persia. His father's sudden death had put an end to the campaign and there is no evidence that there was any formal closure of hostilities with Persia. (A good indication that this may be the truth, are the negotiations from the next emperor Diocletian with Persia early in his reign.) He was well liked by the Roman people and Senate, being an educated and gentle man who was fond of poetry, literature, and oratory. It was these qualities that allowed Numerianus to be controlled by the praetorian prefect who would eventually murder him. To mark his accension, Numerianus was nominated for the ordinary consulship of 284 which he held with his brother.
In March he was in Emesa, and still in good health, but soon afterwards, he fell ill. His staff, including Aper, spread the word that he was suffering an inflammation of the eyes and hence, was travelling in a closed litter. Nobody had heard from the emperor for four days, and only investigated when suspicious smells started to emanate from the imperial litter. Tearing open the curtains of the litter, they discovered the body of the emperor, already some days dead. In all likelihood, the youth had succumbed to illness, and his senior officers were colluding in keeping the matter quiet so that the loyalty of the army might not be tested. The premature discovery of the body led to a military assembly in which the commander of the imperial bodyguard, Valerius Diocles accused Aper of having encompassed Numerianus death. Diocles then vindicated his claim by running Aper through with his sword. The assembled troops took the hint and proclaimed Diocles emperor. Diocles became then Diocletian.
Numerianus death occurred early in November 284. The assembly at which his succession was decided took place on November 20th. He had reigned for about fourteen months, but in all probability ruled for very little of that time. While the Historia Augusta records (or invents) a tradition of Numerianus as an amiable young man and excellent orator, nothing of his personality is in any way betrayed by the scant records of his life and reign that survive.