Sarupya is to attain the form of Divinity. How is this possible? The Vedas say, Brahmavid Brahmaiva Bhavati (the knower of Brahman becomes Brahman). Prahlada, who contemplated on Lord Narayana, became Narayana himself. The dacoit Ratnakara recited the name of Lord Rama and transformed himself into sage Valmiki. Hanuman contemplated on the name of Lord Rama. He is worshipped by the devotees of Rama. (SSS Vol.32 Part I, p. 183)

Sarupya is the assimilation of the form of the deity. (SSB 1979, p. 129)