He opened himself to the artistic avant‑gardes of his time and became co‑founder of the Ziniars group in the 1920s—a group whose name (derived from the zinnia flower) reflects its members’ desire for original, vibrant expression. The Ziniars played a key role in creating the Salon du Sud‑Est in 1925, an event that promoted modern art in the region and encouraged artistic exchanges between Lyon and Paris.
Didier’s interest in the avant‑garde deepened when he discovered the work of Fernand Léger and André Derain, two leading figures of Fauvism and Cubism whose art had a profound influence on him. His active participation in these avant‑garde circles and his involvement in Lyon’s artistic life gradually established him as an important player in the artistic dynamics of the first half of the twentieth century.