He is known to be a part of the Volunteers Fighting Disease, which means his real name is unknown (as members are referred to as siblings only), and he believes that no news is good news, and that a cheerful attitude is better than any medicine.
He skips out when they arrive at Heimlich Hospital to meet up with other members, and they watch in glee as the Bearded Man and Perky Volunteer explain their mottos to the Baudelaires. The Volunteers then enter the hospital to be cleared by Babs, and follow their leader after he receives the patient list.
The Volunteers fall asleep in the hospital lobby, and are awakened by the White-Faced Women with a new patient list. The group then proceeds through the hospital, ignoring the patients' cries for help and opting instead to deliver them balloons and songs.
The Volunteers then gather for a cranioectomy demonstration, in which Faustus is revealed to be Klaus and Sunny in disguise, sneaking in to save their sister. Mattathias then claims that the Baudelaires set the hospital on fire, and he runs with the rest of the group in pursuit of the fleeing children.
He apparently survived the fire, and was summoned to the Hotel Denouement in order to appear as a witness to Count Olaf's trial. He and his fellow Volunteers- minus the Bearded Man- arrive for the trial at Hotel Denouement, sitting together and still smiling brightly.
It is unknown if he survived the subsequent Hotel Denouement Fire.