Ruze Selen el Phiriazar, prince of the theocratic nation Selenfalen, is devoutly devoted to the deity Saint Philia. He bears the weight of public perception, often revered as a divine figure due to his status and appearance—a stark contrast to his younger brother Mare, who endures societal stigma as the "cursed prince." This dynamic fuels Ruze's protective instincts toward Mare, anchoring them both emotionally throughout shared adversity.

Initially presented within aristocratic conventions, Ruze evolves significantly when political conspiracies threaten Selenfalen. He demonstrates resilience by strategically wielding his diplomatic skills, employing his characteristic smile as a deliberate tool to disarm adversaries and ease tensions during critical negotiations. His leadership emerges against external threats, confronting the masked antagonist manipulating Milidonia's king and neutralizing supernatural influences endangering peace.

A pivotal moment reveals Ruze directly challenging Chrom Rem, a former ally complicit in schemes against Selenfalen's sovereignty. Rejecting punitive measures, Ruze instead commands Chrom to remain beside him as atonement, emphasizing accountability through service over retribution—showcasing his commitment to reconciliation and nuanced justice.

Ruze's growth is further marked by his willingness to rely on others: accepting vital support from Ani Inako during diplomatic crises and collaborating with princes from rival nations like Milidonia. His actions amid Selenfalen's internal turmoil—mobilizing resources, shielding Mare from political exploitation, and publicly affirming his brother's legitimacy—solidify his role as a unifying figure who sheds his initial ornamental perception.