When Alfonso II died in 842, his chosen successor, Ramiro I, was in Bardulia, where he was to marry a woman named Paterna.
Upon learning of Nepotian's usurpation, Ramiro gathered an army and began his journey back to Asturias.
In the midst of Ramiro's return, Nepotian and his army composed of Asturians and Basques ambushed him near a bridge that crossed the Narcea river.
He was captured in Pravia by two counts referred to as Escipion and Somnan; as punishment for his transgressions, he was blinded by Ramiro and imprisoned in a monastery.
Likewise, he is sometimes identified as a man also named Nepotian who appears in a charter of King Silo, but if these men were the same, he would have been in his nineties when he usurped the throne.