Doctor Cyril was among the many doctors that worked in the Department of Health in the Parade District. When it became clear that doctor Verloc was unstable, Cyril seeing how Verloc's 'permanent solution' was just leading to people going insane the doctors plotted to find their own solution. Upon learning that a downer whom had managed to break in. He and doctor Oldershaw took this opportunity to capture the downer and test the Coconut joy on him.
Waiting for him behind two doors the doctors overpowered Arthur injecting him and knocking him out. Chaining him up to a chair in a test room and injecting him with the coconut joy. When Arthur recovered, the doctors showed him disturbing images hoping that the joy would be a success.
It didn't but due to the doctors being unable to see what Arthur saw, they would've realized where the plague victims were. When the test still needed improvements the doctors released Arthur and were preparing him to go to his cell. But a malfunction caused the placed to explode Arthur survived, but the two doctors weren't so lucky.