[5] His father Lysimachus was one of the Diadochi of Alexander the Great who was King of Thrace, Asia Minor and Macedonia.
Ptolemy I was another of the Diadochi of Alexander the Great who later founded the Ptolemaic dynasty of Ancient Egypt and Berenice I was the great-niece of the powerful Regent Antipater.
He was also the namesake of his maternal grandmother's first husband Philip,[18] who served as a military officer in the service of Alexander the Great.
After the death of his half-brother, Agathocles’ cousin-wife Lysandra with their children fled to Seleucus I Nicator in Babylon.
[22] Ptolemy Keraunos lived in his father's kingdom as a political exile and, prior to marrying Lysimachus' mother, had murdered Seleucus I in order to gain the power of his former protector and then rushed to Lysimachia where he had himself acclaimed king by the Macedonian army.
[23] The union between Arsinoe II and Ptolemy Keraunos was purely political as they both claimed the Macedonian and Thracian thrones.