For the Middle Ages, a genealogist must resign themselves to the limitations of available sources: the sparseness of information rarely allows for a comprehensive genealogy of even prominent medieval families. Most records provide at best simple male names (and only rarely female) linked together, often with uncertain connections, leaving genealogists to infer family ties based on clues such as Leitnamen (recurring family names). As a result, assigning character or personality to these individuals is nearly impossible. Yet, amidst this era marked by limited documentation, one figure shines brightly: Charlemagne. As one of Europe’s greatest sovereigns, abundant sources mention him, and thanks to Einhard's biography, we gain insights into his persona—not only as king of the Franks and Emperor but also into his private and personal side.

Einhard paints a vivid portrait of the sovereign, even down to his physical appearance: he describes Charlemagne as very tall (a detail confirmed by analyses of his remains in his tomb in Aachen), robust, with a round head supported by a thick neck, large, lively eyes, and an unusually large nose. Though he had a manly demeanor, he spoke with a high-pitched voice.

In terms of character, Charlemagne was highly sociable, easily forming and maintaining friendships, and was inclined toward laughter. This affability is demonstrated by his habit of inviting his entire court to join him in the hot springs at Aachen. Beyond his native Frankish, he learned Latin well, and while he understood Greek, he spoke it poorly. Writing was not one of his strengths. Charlemagne dressed in the Frankish style, refusing to wear other types of clothing except when crowned in Rome; when necessary, he dressed elegantly, but otherwise, he preferred common attire. He despised drunkenness, though not gluttony, as he ate heartily, favoring spit-roasted meat. He was deeply attached to his daughters, keeping them unmarried to avoid parting with them.

Einhard thus presents a "living" Charlemagne, highlighting both his strengths and flaws, moving beyond mere panegyric to offer a rich, nuanced portrayal of the man behind the title.