Dryden Fassa is the eldest son of the Fassa family, one of the oldest and most affluent merchant houses in the kingdom of Asturia. His father, Meiden Fassa, is a noble and an advisor to the King of Asturia, and it is by his arrangement that Dryden is betrothed to the king's youngest daughter, Princess Millerna Aston. Unlike his father, who is described as greedy, Dryden has spent five years traveling abroad, building and running his own lucrative merchant airship convoy, which demonstrates his independent nature and business acumen.

In personality, Dryden is a highly intelligent and curious free spirit who approaches life with a laid-back and irreverent attitude that sets him apart from the more romantic and serious characters of his world. He is a master of sarcasm and verbal wit, often coming across as egotistical, cynical, and brash, which gives him a knack for irritating others who hold reverence for propriety, society, or tradition. Despite this cocky exterior, he is deeply selfless, generous, and romantic at his core. He is a pacifist who hates war and becomes frustrated with politics, preferring economic sanctions as a strategic response to threats rather than military action. His honesty can be blunt, and he is known for speaking what he believes to be the truth, even if it is perceived as rude.

Dryden takes a passionate, scholarly interest in esoteric and arcane topics, such as the legend of Atlantis and the mechanics of Guymelefs. He collects Guymelefs not for their military potential, but for the integrity of their construction. This knowledge and his pragmatism make him a valuable asset to the group. When Van is severely injured due to his bond with the damaged Escaflowne, Dryden deduces that the only way to save the young king's life is to repair the Guymelef. He uses his expertise to summon the mysterious Ispano, who are capable of the repairs, and when they demand an impossibly high price, Dryden selflessly offers his entire merchant convoy as payment without hesitation. This act, which costs him a fortune accumulated over five years, is done to save a relative stranger, demonstrating his profound generosity. He also plays a crucial role by borrowing and interpreting the diary of Leon Schezar, the father of Allen Schezar, which is written in the language of the Mystic Moon, helping the group on their quest to find Atlantis and its secrets.

Dryden's central relationship is with his betrothed, Princess Millerna. He falls in love with her and spends much of the story trying to win her affections, often by bluntly advertising his wealth, intelligence, and looks. Although he is confident and persistent, Millerna's heart belongs to Allen Schezar. Their relationship reaches a turning point during their disrupted wedding day when the Zaibach empire attacks. During the chaos, Dryden injures himself protecting Millerna, who in turn rips the sleeves from her wedding dress to tend to his wounds. Later, after realizing that her love for Allen has not faded, Dryden demonstrates his romantic and selfless nature by releasing Millerna from their marriage. He gives her back her wedding ring, telling her he is not yet worthy of her, and vows to leave and travel until he becomes a man deserving of her love, promising to make her fall for him someday. He also serves as a foil to the chivalrous but rigid Allen Schezar; where Allen represents order and propriety, Dryden embodies irreverence, disorder, and casual freedom, which naturally leads to a tense and confrontational dynamic between them.

Throughout the story, Dryden undergoes significant development. Initially introduced as a seemingly idle, wealthy playboy, he is quickly revealed to be a competent and decisive leader. His selfless act of sacrificing his fleet is a catalyst for his growth, but his most profound change comes from his relationship with Millerna. By choosing to let her go, he transforms from a suitor trying to win a prize into a man focused on bettering himself for the sake of love. By the end of the war, he has become the king of Astoria, a far more competent and open-minded ruler than his predecessor, willing to listen to former enemies like Folken and negotiate for peace.

Dryden has several notable abilities. His primary strength is his extraordinary intelligence and vast knowledge, particularly concerning history, ancient civilizations like Atlantis, and Guymelef technology. He is a shrewd and successful merchant, demonstrating exceptional skill in business and negotiation. Furthermore, he is proficient in reading the language of the Mystic Moon, a skill that proves vital for deciphering key texts.