Drachm - Ariarathes IX Eusebes Philopator

(en) Ariarathes IX was one of the many sons of Mithradates VI, king of Pontos, who used his son as a puppet ruler for Cappadocia. Ariarthes was only eight years of age when his father assigned him to a task that will eventually claim his life. According to O. Mørkholm (in his articles in Essays Robinson and QT 1975), the obverses on the last two years of Ariarathes' mint A coinage carried a portrait of the Pontic king rather than his son. The purpose of the change is uncertain, but it may have been done in relation to a revolt of Cappadocian nationalists. These nationalists recalled the young Ariarathes VIII and promoted him as their king, in opposition to Mithradates VI and his puppet king. This revolt was quickly suppressed, and Mørkholm argued that in the aftermath Mithradates had his portrait placed upon the coinage as a more overt pronouncement of his rule over the Cappadocians via his son. Sources: http://www.forumancientcoins.com/catalog/roman-and-greek-coins.asp?zpg=24904 & https://www.cngcoins.com/Coin.aspx?CoinID=71784.