The "hook-nosed" younger son of Demetrius II & Cleopatra Thea was co-regent with his mother after his father's death (125 BCE).  When she died (ca. 120 BCE) he was challenged by his half-brother, Antiochus IX & in 116 BCE agreed to divide the Seleucid kingdom with him. The lingering feud between the half-brothers allowed Johanan Hyrcanus to reassert Jewish independence & bring Samaria & Idumea under Jerusalem's control.

References: Josephus, Antiquities 13.269-273, 261-263, 325, 365.
                  _____, War  1.65.
                  Appian, History of Rome: Syrian Wars 68.
                   Justin, Epitome 39.1-2.

Other resources on line:

• Antiochus VIII Grypus - Jona Lendering chronicles events & lists primary resources [Livius: Articles on Ancient History].

• Antiochus VIII Grypus - article in Wikipedia's web.

The profile of Antiochus VIII on the face of this tetradrachma minted at Ptolemaïs shows why he was popularly dubbed "hooked nose."  The inscription on the back, however, reveals his more grandiose self-image: Basileos Antiochou Epiphanous ["of King Antiochus, (God) Manifest"].  Grypus left his claim to divinity implicit. Yet the fact that the reverse side of his coins regularly featured the often nude figure of Zeus--usually standing bearing a scepter & star with crescent moon over his head--leaves little doubt that even in Palestine, like Antiochus IV, he promoted himself as incarnation of the supreme god.

For high resolution images of this and other coins of Antiochus VIII see Ancient Coinage of Seleucia, Antiochos VIII in David Surber's excellent ancient coins website: Wildwinds.