I love German accents, and I can think of a lot of interesting characters who could sport them. Scientist/engineer is a common archetype in American media. So is hot girl/super-model (Heidi Klum anybody?). You could introduce them as Colony or Boulder survivors. Or soldiers; when I was at Fort Irwin there was a Bundeswehr liaison team stationed there, along with some British, French, Israeli and Australian personnel.

I think it would be fun to have two German characters, one from Hannover and one from Stuttgart, who have to talk to one-another in English because they can't understand each other's German accents.