Family giving everything they have to save younger brother

SEATTLE -- We hear the phrase "brotherly love" all the time, and we usually don't even pause to consider what it really means.

But one local mother knows what it means better than most. The brothers are her sons, and they've been forced into an extraordinary situation: Taking turns saving each other's life.

Kristina Smith is at the breaking point and her family is on the brink. Hope is a slippery thing, and Smith is hanging on for dear life.

"it's the hardest thing I hope I ever have to do," Smith said.

Her boys are Smith's salvation. They are away from her now, staying with family. The brothers are thick as thieves.

"Best friends for life, and you're supposed to look out for each other," said Noah.

They're growing up sooner than they should, missing their mother and keeping each other alive.

Smith is in Seattle tending to Liam, her two year old who is puffed up from steroids and fighting a disease as nasty and deadly as its name.

It's called hemophagocytic lymphohistiocytosis. With it, the immune system turns on, but can't turn off. So the body is at war with itself, attacking its own organs.

"In it's full form, these are the sickest kids you will see. They're very very ill," Liam's doctor said.

The only chance is a bone marrow transplant. It was Hunter who stepped up the first time a year ago.

"They stuck a -- they never really told me what it was -- like a big needle, into my back right there. There's still lumps right there from it," Hunter said.

This time Noah will step up as the marrow donor.

"Just saving Liam," Noah said. "And I love him so much. He means everything,"

Big brothers need to be brave, but it's tough.

"These boys don't even, it's not even a question to them. They just do it. We're going to save our brother's life and I couldn't ask for more. I'm so proud to be their mother," Smith.

Liam has been sick his whole life, and he hasn't been outdoors for 6 months. But he likes to wrestle around with is brothers, has a thing for Elmo and when he dances, the whole world lights up.

Noah arrives early on the morning of the transplant to do the things he needs to do. For Liam, it's another morning in the hospital.

He doesn't know he's waiting to have his life saved.

Two hours later, Noah emerges. He's pale and groggy, but proud of himself.

"Makes me really happy," he said. "That's the whole reason I did it, to save him."

The marrow arrives in bags, scarlet drops of hope passing from one brother to another.

It's a gift as profound as brotherhood itself.

"After I give you this boo, you can go home, you can go play, you can go outside," Noah said to his little brother.

Smith is full of love, family and hope, and she continues to believe things will be alright.

"I can't give up, that's just not an option," she said. "And I want them to know that. I don't want them ever to give up on anything."

So far, little Liam is doing well. He's out of the hospital and staying in the Ronald McDonald house with his mom. The rest of the boys are still living with relatives in Woodland.