Which orphaned cousin is in love with Nikolai Rostov?

Which orphaned cousin is in love with Nikolai Rostov? The answer is Sonya Rostova.

Sonya is the orphaned niece of Count and Countess Rostov and is raised alongside their children, including Nikolai, Natasha, Vera, and Petya. She and Nikolai grow up close, and their affection develops into a long-standing romantic attachment.

Nikolai promises himself to Sonya for much of the novel, but the relationship is constrained by money and family expectations. The Rostovs’ financial troubles make a wealthy marriage attractive, while Sonya’s dependent position makes her reluctant to demand a future that could burden the family who raised her.

Eventually, Sonya gives up the possibility of marrying Nikolai, allowing him to marry Princess Marya Bolkonskaya. This is not simply a failed romance: it reflects Sonya’s defining willingness to sacrifice her own hopes for the Rostov household. Marya is Nikolai’s eventual wife, but Sonya is the cousin who loves him first.