Rossa was born to Connor and Moira Rossa on Galen IV in 2353. Four years later, in an attack during the Galen border conflicts, Rossa's parents were killed by Talarians. As per Talarian rights, Rossa was adopted by a Talarian named Endar, who welcomed him into his family like a son. He was integrated into Talarian society, renamed Jono, very much unaware of his fading human side.
In 2367, he and several Talarian youths were training on a Talarian starship when it became disabled. The Starfleet starship USS Enterprise-D rescued them. During his time aboard the Enterprise, Captain Jean-Luc Picard attempted to renew Jono's interest in his humanity, even going as far as to get him into contact with his paternal grandmother, Admiral Connaught Rossa.
Torn between his true identity and his adoptive culture, Jono lashed out, attempting to stab Picard, in an attempt to be put to death for his actions and end the dilemma. In the end, with the decision up to Jono, he chose to return with Endar to Talarian society. (TNG: "Suddenly Human")