Back at his school, Mount Aiden, Nero was very well known, and though popular wouldn't be the word he'd use to describe himself, he was influential among the students and even the teachers. This was because he had proven himself highly competent in every relevant field, and yet was friendly and approachable, always having an inviting and welcoming smile on his face.
His grades were not notch, combat training was his best class, was extremely driven and always did more than was necessary. In a school environment, especially one where everyone was driven since they knew they'd get military service sooner or later, such behaviour made him popular.