Operation North Pole went off without a hitch over the weekend, as hundreds of volunteers and first responders teamed up to give children battling serious illnesses a Christmas they'll never forget.

Kids will be kids, no matter where they are, and brothers will be brothers. That's how it is for Danny and Tommy Fennig. The 8-year-old twins were born two minutes apart.

"I'm the older brother. My brother's the younger brother," Danny said.

Danny always keeps a close eye on Tommy, who's always wearing his red Mario hat.

"It has all my memories in it," Tommy said.

Tommy's hat is full of memories, but was able to squeeze in some more on a day of sweet surprises on Saturday, starting inside the Stephens Convention Center in Rosemont with a meet-and-greet with first responders.

Then, dozens of families like the Fennigs boarded buses bound for the train station with a police escort, for a ride with Santa Claus on a special Metra train.

Tickets were reserved for kids who've been on a tough journey.

"Tommy, my son, has brain cancer; and so that is why we're on the train," Vanessa Fennig said.

Moms like Vanessa are grateful for this gift; a day not focused on a diagnosis, but a destination.

"We are headed to the North Pole. We've got some magical loops to get through to find Santa," one of Santa's elves said.

On the Christmas train, snowball fights are encouraged, and so is singing at the top of your lungs.

"It's obnoxious, but in an awesome way," said Tommy's father, Dave.

Every stop along the way, families see and feel support from countless volunteers.

"This is really special to have all of these people out for all of us. It's a very special moment," Dave said.

The end of the train ride – is just the beginning. Not even Santa gets this warm a welcome. The North Pole belongs to kids and their families to explore.