Appearances in the seasons 2012-14 include Robert Carsen's production of Giorgio Batistelli's Richard III and Philippe Fenelon's JJR Citoyen de Genève, both with the Opera de Genève and Oliver Knussen's 60th birthday production by Netia Jones, of his completed Where the Wild Things Are and Higglety Pigglety Pop, opening the 2012 Aldeburgh Festival conducted by Ryan Wigglesworth, and then with Gustavo Dudamel and the LA Philharmonic in Los Angeles. More recently, Christopher played the Schoolmaster and Mosquito in Imbal Pinto and Avshalom Pollack's production of Janacek's Cunning Little Vixen for Bergen National Opera, going on to play Il Podestá in Harry Fehr's critically acclaimed production of Mozart's La Finta Giardiniera for Buxton Festival Opera, which has since been nominated for the Manchester Evening News Award.

Christopher made his Covent Garden debut stepping into performances (and live radio relay) of Trevor Nunn's production of Nicholas Maw's Sophie's Choice, under the baton of Sir Simon Rattle, and then went on to take over the role of Caliban in Thomas Adès' The Tempest to critical acclaim, this time also on a television broadcast, and has gone on sing the role many times since. Other appearances of note include David Poutney's production of Bernd Alois Zimmermann's Die Soldaten with the Bochum Ruhrtriennale and at the Lincoln Centre Festival New York, Molqi in Tony Palmer's production of The Death of Klinghoffer in Helsinki, and Bob Boles in David Alden's award winning Peter Grimes for Vlaamse Opera.