It's Thursday night and Day 12 of the election campaign. The Conservative plane has flown this week from Ottawa to Quebec City, then on to Toronto, Vancouver, Edmonton, Regina, and Winnipeg. As we fly to Hay River, N.W.T., we're all very tired. Exhausted, actually.

Suddenly, an unfamiliar voice is heard on the in-flight intercom.

"We’re going to have a contest,” he says.

It's Ben Harper at the front of the plane, holding a Winnipeg Jets jersey.

"What is the distance from Hay River to Iqaluit?" he asks. He pauses for effect, then adds "in nautical miles" and laughs. “The closest number gets the Jersey.” Someone else shouts out another rule: “The closest without going over."

The Harper children have been campaigning with their father for a decade -- they started as small children and are now young adults. Ben is 19 and Rachel 16, and they appear to be enjoying this campaign.

"They're really into this one," one campaign veteran says. "They're older. They get it."

Rachel is a little more reserved, and even seems a bit shy. I caught a glimpse of her this week passing through the lobby of a hotel. As she tried to blend into the crowd, I gave her a smile and she politely smiled back, but kept walking.

Ben can be seen mixing it up with some of the staffers and is also in the back rooms helping his dad. He was there for debate prep and those close to Harper say he offers advice and also helps keep things light.

This is how they are spending their summer vacation. Perhaps it’s not their first choice, but they can blame their dad for calling an early -- really early -- election.

In Hay River, Harper took a moment to refer specifically to his children. "I am proud to have Ben and Rachel with me,” he told a small gathering of supporters. "This is their first visit to Hay River and it's great for them to be here."

Rachel and Ben Harper

And the team likes having them here too. Those close to Harper say he's more relaxed with his family at his side. Laureen, of course, has always travelled during campaigns, but insiders say Ben and Rachel add some levity.

The brother-sister duo sit at the front of the plane with their parents, but they're not always still. They could be seen volleying a ball back and forth using the seat between them as a net. All the while, their father is sitting somewhere near them, no doubt preparing for the next whistle stop. "He loves it," one staffer said. "The boss is having fun."

It's not always fun for Harper as his campaign continues to be dogged by questions about the Duffy deal from the very reporters travelling on the Conservative plane.

Insiders say Ben is protective of his father, but he understands the game.

So, on this Thursday night flight the game is guessing the number of nautical miles from Hay River to Iqaluit and Ben Harper, who is the spitting image of his father, has turned a grumpy plane into enthusiastic contestants.

Even though the young Harper has sat day after day listening to the media pound pointed questions at his dad, he walks to the back of the plane where we sit. It’s his first foray into media territory and he cracks a few jokes as he collects the sheets of paper with our final answers.

As he announces the winner -- a member of Harper's security detail who guessed 1,300 nautical miles when the answer was 1,303 -- the young Harper seems genuinely pleased to present the jersey. His father, no doubt, is genuinely proud.

At a final stop Iqaluit Friday evening, Harper tells a small group of supporters that it’s Ben's first trip north, but he then looks at his daughter -- who has her mother's features -- and says it’s Rachel’s second trip: "She was here when she was a little younger."

We found a photo from that trip in our archives, for Sept. 2008 in Iqaluit:

Stephen Harper, Laureen, Rachel in Nunavut in 2008

File photo: Conservative Leader Stephen Harper, his wife Laureen, and their daughter Rachel walk along the shoreline in Iqaluit, Nunavut on Saturday, Sept. 20, 2008. (THE CANADIAN PRESS/Paul Chiasson)