Thierry encountered Giselle just after she first received her sigil. He was interested in her from the start but she was swayed by Darrow. Once she learned of Darrow's machinations, her interests turned back to Thierry. However after spending much time with Giselle's older sister Genevieve, the two of them began a relationship. It didn't help that Giselle wasn't really being an attentive girlfriend or really his style.
When not looking out for Giselle, Thierry is an artist.