Ophelia in Hamlet, a character she played previously, for a new rendition of the Shakespearean classic. In 2003, she joined the ensemble at Toneelgroep Amsterdam, under the direction of future long-time collaborator Ivo van Hove. Around that time she also completed her final performance for De Theatercompagnie, with a new production of The Seagull, where she played Nina. In her first year, with the Toneelgroep Amsterdam, she starred in two plays: She played Irina in the Three Sisters, based upon the play of Anton Chekhov of the same name, and Eugene O'Neill's Mourning Becomes Electra, a co-production with the Toneelschuur, for the latter performance, in which she played Lavinia, she was nominated for a Theo d'Or for "Best Female Actress" in 2004. On television she starred in two telefilms, she played Ewouds's girlfriend in Boy Ecury and Hostess Patty in Het wonder van Máxima, they were aired on public television on 2 and 9 April respectively. Reijn had three big screen releases in 2003. Her first appearance was as Polleke's mother, Tina, in the family film Polleke, a film adaption of Guus Kuijer's children's book. At first, she was bewildered why she approached by director Ineke Houtman for the role of Polleke's mother, at the time she viewed herself too young to play a mother, but later accepted the role when delving into the character's story. The movie premiered on October, 11 as the opening film of the Cinekid festival. Her next feature film was with director-writer Alex van Warmerdam, called Grimm, in which she had the female leading role. The story is loosely based on Grimm Brothers's Brother and Sister, in which a brother and sister are abandoned by their father in a forest; in a note their mother urges them to go to Spain to meet up with their uncle. The movie was first shown at SSIF, before released nationwide in the Dutch theaters in early December. Compared to the directors earlier work, Grimm was a critical and financial disappointment. Dissatisfied with the original cut, director Alex van Warmerdam together with editor Job ter Burg went back to the original and reworked the entire film. The new cut premiered at 2019's Netherlands Film Festival. Reijn then starred in Maarten Treurniet's directorial debut Father's Affair, where she played Ellen, the girlfriend of Peter Paul Muller's character and best friend of his deceased wife, who is notified by his GP