After the doctor allowed Arya to leave the hospital, he didn't immediately return to Indonesia as originally planned because he still didn't believe that he was in Greece at that time.
Arya also decided to stay for a while in the hospital until he found out everything related to his past. Before he met Alexa whose soul was exchanged with Ryung Hwa, he already knew that at that time he was inside Ryan's body.
Like Ryan, Arya was very surprised when he saw his own reflection in the mirror. The face of the person he hated so much before he had amnesia, was clearly visible in the mirror, he didn't understand why his face could turn into Ryan's face.
Arya's memory was partly lost, but he could remember whose face she was seeing at that moment. To make sure everything that confused him, Arya tried to contact Diana by asking the hospital for help.