Why does Brody's wife call him by his surname?

Question

I don't think I've ever heard Brody's wife call him "Nicholas" throughout the first two seasons of Homeland. Why does she always call him by his surname?

Answer 1

Here is Nicolas Brody's (Damian Lewis) answer on it -

Q. Why does the wife call him Brody?

A. [Laughs] Morena’s been asking that all season. “Why don’t I call him Nick?” I’m a boarding-school-educated Brit so people have been calling me by my last name forever. So it doesn’t seem that weird to me. I think the writers see it as a term of endearment.

(Source: www.nytimes.com)

By the way, it's very common for military wives to call their husband by their last name.