Check out this revealing exchange with radio host Don Imus on January 24 about how Broadwell got to know Petraeus:

BROADWELL: He came to speak at Harvard while he was a Commander at Fort Leavenworth and he was writing the Field Manual. And I was studying at the time, and a group of students was asked to meet with him. After he gave a presentation, to the entire student body and I went up to him and said I'm working on this research and I'd love to get your feedback or connect with folks in your military organizations to share these ideas and he gave me his card, and we kept in touch. He does a lot of mentoring like that, he's willing to reach out and take any good idea out there and put it into the organization if it makes sense.

So, I decided then to pursue my Ph.d. and reached out to him and asked if I could interview him for the case that I mentioned earlier. We kept in touch then, basically via e-mail and occasionally, if I was in Washington, and he was in Washington, we'd go for a run and the book preface, once you read it, Imus, you'll see that one of our first--

IMUS: Wait, I mean, I-- I don't know if you're aware of this, but I'm currently battling cancer so I may not have--

BROADWELL: A good time to read.

IMUS: Is he married? [emphasis added]

BROADWELL: He is married to Holly Petraeus, who is a wonderful Military spouse and done so much for their children and for children of fallen soldiers, I respect her immensely.

IMUS: So he must have liked you obviously and you obviously liked him, I guess.

BROADWELL: Yes, it was a-- you know, as I said earlier, he has a number of mentees and that's one thing that's different when you compare him to other Senior Commanders, he looks at the organization, the military as an organization and is willing to take ideas from any rank, not that my ideas were that good, but, yeah, we had a lot of rapport. I think some of that comes from a common ground of having gone to West Point.