One of his first noted roles was in the television series Jamais deux sans toi as Bernie Lacasse, one of the first gay characters ever depicted in a Quebec television series.[3]
In recent years, Thériault has suffered from serious clinical depression, confining himself to his own home.[4] The efforts of his friends and family to guide him toward treatment and healing were profiled in the 2021 documentary film Dehors Serge dehors.[5]