Who is Joachim Messner from Bel Canto: A Novel and what is their importance?

Joachim Messner is employed as a negotiator for the Swiss Red Cross. He is described as a pale man, who is on vacation in the country when he is ordered to handle the negotiations between the terrorists and the government. Messner's Spanish is lacking, which forces him to rely on Gen's translating abilities. He consistently urges the terrorists to give up and walk away, telling them that these situations never end well, and by the end of the story, he even feels sympathy for them.