 Working with Pierre Trépos, he created hundreds of dialogues, many of them between two stock characters, Gwilhou Vihan and Jakez Kroc'hen.In 1948 he was the co-founder, with François Bégot and Jo Halleguen, of , a major summer festival of Breton life.The theatre was Helias's favourite "genre", as he was convinced that the Breton reality was primarily a spoken one, so that it could best be captured by drama, and much of his early work was in the form of plays and scripts for radio.