The writer and executive producer of Grey's Anatomy and its spin-off, Private Practice, says she has always liked to represent people from all walks of life on her shows.
Having a Kiwi doctor on her series about six young doctors working in a remote, South American jungle - yes the Shortland Street graduate is almost in Guatemala now - added to the intrigue of what they were doing there, she says.
Henderson says the idea of acting in his natural accent is what initially made the role of Ben Keeton, a deviant doctor, hugely attractive to him.
But as it turned out, the American network wasn't convinced a broad New Zealand accent would fly with viewers, so he had to articulate a little more than usual and tweak a few vowels.
He moved to the States to pursue film and theatre opportunities and has since appeared in films The Ring, Little Fish, and closer to home, Home By Christmas.
Henderson says his decision to move back to television was partly fuelled by the prospect of a more normal life, which suited his priorities as a 30-something.
"I kind of grew tired of living in hotel rooms and being away from my friends and my family and my dog."
And, admittedly, moving to Hawaii also made the prospect more attractive.
"I'm very happy being in Hawaii, I think they were thinking of trying other places but Hawaii presented the best backdrop.
"I did actually suggest New Zealand, but they weren't keen.
"I feel very blessed to be there.
"There are beautiful beaches and people.
"Having lived in mainland America for so long and being from New Zealand, Hawaii offered me a very good balance."
He is learning jungle survival techniques for his role of jungle-healer, but admits these days he prefers to leave the Tarzan-like stunts to the doubles.
"To be honest, in my 30s, I'm over the whole, 'I'll do my own stunts thing'.
In my 20s I thought it was cool, but now I'm like 'Nah, you do it mate, make me look really good'."
Henderson says he found researching the role fascinating as he read the biographies of doctors who had worked in jungle and combat zones and had to rely on natural resources to save lives.
There will be a focus on these procedures and the personalities of the six doctors, but Ben Keeton's reasons for being on the island will remain vague until further down the track.
And, yes, it can be expected that like most male doctors on Rhimes-created medical shows, he will also have to reveal his torso.
"To be honest, there have been quite a few times when it has been suggested that maybe I would be shirtless for a scene.
"I managed to convince them that would not be logical, so [am] trying to keep it in the realms of reality."
Is Ben going to play to the Kiwi stereotype of not being of the most romantic stock?
"Well, I'm romantic," Henderson says, indignantly, then adds: "But yeah, there's a little bit of that in this character.
"He is a very practical guy, but there is something that happens with Ryan [played by Twilight's Rachelle Lefevre] that forces him to open up in a way he hasn't before."
And the drama of saving lives will be entwined in plenty of lust and complicated relationships.
"I think we are definitely in for our fair share of bed-hopping, or tree-hopping as it is in this case."
• Off the Map premieres tonight at 9.30pm on TV2.
