Meleager was killed, and a compromise was engineered: Arrhidaeus would become king, with the name of Philip, and he would be joined by Roxana's yet-unborn child as co-sovereign should that child prove a male.
This eventuality did indeed arise and resulted in Roxana's son, Alexander, becoming with his uncle Phillip III co-sovereign on the throne of Macedon.
Even though Arrhidaeus and Alexander were about the same age, Arrhidaeus appears never to have been a danger as an alternative choice for Alexander's succession to Philip II; nevertheless, when the Persian satrap of Caria, Pixodarus, proposed his daughter in marriage to Philip, the king declined, offering his son Arrhidaeus as husband instead, and Alexander thought it prudent to block the dynastic union (which might have produced a possible future heir to Philip's domain before Alexander himself did), resulting in considerable irritation on the part of his father (337 BC).
Arrhidaeus' whereabouts during the reign of his brother Alexander are unclear from the extant sources; what is certain is that no civil or military command was given to him in those thirteen years (336–323 BC).
Arrhidaeus is also a main character in Annabel Lyon's novel The Golden Mean.
In it, the young Arrhidaeus is tutored by Aristotle while he also mentors his younger half-brother, the future Alexander the Great.
In 1977, important excavations were made near Vergina leading to the discovery of a two-chambered royal tomb, with an almost perfectly preserved male skeleton.
Manolis Andronikos, the chief archaeologist at the site, along with a number of other archaeologists, decided it was the skeleton of Philip II, but others have disputed this attribution and instead proposed it to be the remains of Philip Arrhidaeus.
Named Arrhidaeus at birth, he assumed the name Philip when he ascended to the throne.
As Arrhidaeus grew older it became apparent that he had mild learning difficulties.
Golden Larnax (Chrysi Larnaka) (with the Sun of Vergina on the lid) that contains the remains (bones) from the burial of King Philip II of Macedonia and the royal golden wreath.