Seleucus V Philometor

The Seleucid king Seleucus V Philometor (Greek: Σέλευκος Ε΄ ὁ Φιλομήτωρ; 126/125 BC), ruler of the Hellenistic Seleucid kingdom, was the eldest son of Demetrius II Nicator and Cleopatra Thea. The epithet Philometor means "mother-loving" and in the Hellenistic world usually indicated that the mother acted as co-regent for the prince.

Biography
Just before Antiochus VII Sidetes died fighting the Parthian Empire in late 129, the Parthian king Phraates II had released Demetrius II, who entered Syria in ca. September 129. This forced Seleucus V's half-brother Antiochus IX to flee to Cyzicus. Cleopatra Thea remarried Demetrius and reunited him with his two sons, Seleucus V and Antiochus VIII.

The Parthians captured Antiochus VII's son, also named Seleucus, and Laodice, Seleucus V's sister, who had accompanied the fallen king on campaign. Phraates married Laodice, and showed great favor to Seleucus, son of Antiochus VII. While Demetrius II was preoccupied fighting the usurper Alexander II Zabinas, the Parthians sent this Seleucus back to Syria, hoping he could take the throne as their puppet king. The attempt failed, and he spent the rest of his life in Parthia.

Instead, after his father was murdered outside of Tyre in 125, Seleucus V claimed the throne as the eldest son of Demetrius II; however, he was soon killed by his own mother. According to Appian, Cleopatra Thea had aided in the death of Demetrius and feared that Seleucus V might avenge his father. This encouraged her to remove Seleucus in favor of his younger brother, Antiochus VIII.