Osaria was the Principle of the Lorien Academy, an education institution attended by Sandor.
When Sandor is caught at The Chimæra by Professor Endym, Osaria is made aware of his misdeeds, including tampering with the Academy's Truency Register as well as the The Chimæra's security systems to allow him entrance. She calls his parents to discuss his next steps following his expulsion.
Though disappointed, Osaria is secretly impressed by Sandor's actions; telling him that he is the Academy's best student and even though tampering with security systems is highly illegal, it does show a certain amount of ingenuity.
Osaria would have been killed by Mogadorians during the Invasion.