Prince Aegon Targaryen—affectionately nicknamed "Egg" during his youth while traveling incognito—is the younger biological brother of Maester Aemon (born Prince Aemon Targaryen). They were both sons of Maekar I Targaryen, meaning they shared a direct sibling bond before Aemon chose to renounce his claims to the Iron Throne, join the Night's Watch, and spend his life serving dutifully as a humble maester at Castle Black.