I'd interviewed writer/producer Hart Hanson by phone a couple of years ago, before Bones had been renewed for a second season, before it was clear it would be. So attending his Master Class this month at the Banff World Television Festival, I thought I knew what to expect from the Master Teacher: polite, restrained, and speaking in carefully crafted key messages. I was dead wrong, and happy about it.

"I don't think David (Boreanaz) would mind me telling this story. I'll have to ask him some day," the hilariously tangential and irreverent Hanson said at one point before relating a not-in-the-key-messages anecdote about his leading man.

The former Buffy The Vampire Slayer and Angel star was cast first. Hanson was ready to offer him the job based on those roles, but naturally met with him first. "I thought, he could be funny. I was wrong – I underestimated him. He can be very funny. But the meeting with him was just disastrous," Hanson related. "I now know, if you're ever going to talk to David, do not bring up Angel. He does not want to discuss Angel. And I think the first word I said to him was 'Angel!'"

Still scrambling for a female lead four days before shooting the pilot, Hanson was convinced to see a little-known actress named Emily Deschanel. "She was tall, she had a deep voice, she has gravity, she was 30 at that point, or 29. So you could believe her as a scientist, which was kind of tough with some of the actresses we saw," he commented. "It turned out that she could be funny and she looks like Grace Kelly."

But Boreanaz was set on another actress for the role. "David's a very strong-willed man. So he — I won't say sabotaged — he challenged Emily to rise to the occasion by advancing on her. David's about 6'1" and about 200 pounds of shoulders with pecs attached," he laughed. "He advanced on her in the test, and Emily stepped right toward him and they had one of the exchanges from the pilot."

Hanson felt the chemistry instantly, and the Booth/Brennan pairing was brought to life. The initial concept, since Boreanaz hadn't wanted to work full time on a series again, was that Bones would have worked with Booth for about half the episodes, and with various other cops for the other half. "I don't know what changed his mind," Hanson said about the actor's decision to sign on full time. "Maybe because Emily stepped into him like that: 'I have to take her down in the first episode.'"