Ethan

From Memory Alpha, the free Star Trek reference.

Ethan was a young boy who was a prisoner in a Romulan laboratory along with Commander William T. Riker. It would later be discovered that he was the key figure in a holographic simulation created by Barash on the planet Alpha Onias III.

"Ethan" was in fact Barash himself, who was merely seeking interaction with Riker. He had been isolated for several years in a holographic environment that responded to his thoughts and attempted to fulfill his desires. The only thing it couldn't do is provide him interactions with other real beings.

During this same visit to Alpha Onias III, Barash had also appeared as Jean-Luc Riker. (TNG: "Future Imperfect")

Ethan was played by actor Chris Demetral.