A lot has been written about writing with accents. Do you spell the words the way the character would say it and risk having the reader not understand? Do you just suggest the accent, by say, making your German character not use contractions, and use occasional German phrases(which also could be a risk for losing the reader?)
It’s a fun debate but in the end, what I think is more interesting is the character’s reactions to each other’s accents. Let me give you an example. I had a Southern friend who could say just about anything, and because she said it in that cute drawl, people were never offended. She was the most blunt person I had ever met and people loved her.
On the other hand, I have had friends from New York or the Northeast, who talked so fast, and gestured so wildly, that I could start to take offense well before they finish. Accent, the pace at which someone talks, their use of vocabulary matters. And it’s harder to suggest than you might think. But having a character react to that way of speaking, could make it easier.