Gaius Octavius was born on September 23, 63 BC, and though of distant relation to Caesar, his eventual rise to prominence was unexpected. He was the son of a 'new man' bearing the same name from Velitrae in Latium. His father had reached the rank of praetor before dying when Octavian was a boy of only 4 years old, just as Caesar was launching his war in Gaul. His father was married to Atia, the daughter of a somewhat obscure Senator, M. Atius Balbus and Julia, sister of Julius Caesar, making him the great nephew of the dictator. There were other first nephews, but Caesar didn't seem to hold them in as high regard as the young Octavian, though one, Q. Pedius, did serve Caesar as a legate. Despite his relation to Caesar, there was some questionable lineage throughout his family.
Later opponents, Marc Antony included, attacked his heritage by claiming his ancestors were freedmen and moneychangers, not the sort of lineage that one might expect from a rising star in Roman politics. Suetonius claims that Octavian carried another surname as a youth, Thurinus. This, Suetonius claims, either represented Octavian's historical familial roots, or the place where his father bested remnants of slave armies while he served as governor of Macedonia. Suetonius even reports that he came into a statue of Octavian as a boy bearing the inscription Thurinus, which he promptly gifted to the Emperor Hadrian, who prized it highly. Whatever the case, some evidence suggests that opponents like Antony may have used this surname against Octavian.
At the age of twelve (51 BC), Octavian's grandmother and sister of Caesar, died, ushering him into his first major public appearance. He delivered her eulogy, and like many other young political hopefuls, this was the first opportunity to make a mark on both the aristocracy and the common masses alike. While young Octavian was certainly noticed by Caesar at some point, evidence of direct involvement is conflicting. Octavian was coming into adulthood just as Caesar was embroiled in Gaul and in the Civil War that followed, and there certainly wouldn't have been much time for camaraderie. With Octavian's age, and reports of sickliness as a child, contact must have been limited. This, however, didn't stop Caesar from having an impact on the young man's career. In 48 BC, Octavius was appointed as a pontiff (priest) at the tender age of 15. It's possible the Caesar planned to take his protégé with him to Africa to face of against the Republicans there, but either sickness, or an over protective mother shot down this idea.
In 46 BC, Octavian took part in Caesar's triumphal parades in Rome, earning himself some military award, despite taking no part in the effort. Clearly this shows that Caesar at least had some design on his great nephew's future. The following year Octavian followed Caesar to Spain, where the dictator conducted the last battle of his career against the sons of Pompey at Munda. Though Octavian himself took little part in the actual military aspect of this campaign, his journey to join Caesar seems a significant development in the relationship. While en route, Octavian was faced with difficulties in avoiding enemy resistance, including a shipwreck which could've been disastrous. When the two finally crossed paths, Caesar was apparently very pleased with his nephew's daring determination and courage. Other than Caesar's short triumphal visit to Rome, this period in Spain was likely the first time the two were truly able to foster a serious relationship. If at any time, this was the chance for Octavian to impress Caesar, and for Caesar to bring the young man under his wing. While there is little historical documentation, Octavian likely learned a great deal about provincial administration, warfare and political manipulation while a part of his uncle's entourage. Nicolaus of Damascus, though his account is unreliable at best, indicates that Octavian was so firmly entrenched with Caesar that he was able to have considerable influence. In one example, Nicolaus states that Octavian begged a pardon for the brother of his great boyhood friend, Marcus Vipsanius Agrippa, who had served under Cato in Africa. Despite beginning to retract on the number of pardons issued by this time in the civil war (as many who were pardoned would continue to fight), Caesar relented, and may have helped cement a lifetime friendship with the two future leaders of Rome.
By the end of the campaign in Spain, Octavian was sent to Apollonia in Illyricum to further his studies, along with his friend Agrippa. Here he was to continue his education, while waiting to accompany Caesar on a campaign against the Dacians and the Parthians. Octavian was still a very minor player in the politics of Rome at this point, but his star was certainly on the rise. Caesar, having selected various political offices years in advance (one of many slights against Republican tradition), had slotted his nephew to serve as his right hand man, or master of horse, in the year 43 or 42 BC. At the age of 20 or 21, Octavian was expected to occupy the second most powerful position in the Roman world, but fate, and the Ides of March would have a different plan.