She has lost her golden hair and when strangers enter her room at The Hospital for Sick Children, she pulls her grey hoodie with the pink heart over her head and face and crosses her arms across her chest.

Silence.

On the hospital bed in front of her is a cardboard folder decorated with hearts and held fast with tape.

Coaxed into peeking out from under the hoodie, Sarah explains that the cardboard folder is for her mom and her new brother and no one — NO ONE — can touch it. In fact, she needs more tape so she can close it more securely. Where is the tape?

Her father, Mark Watkin, produces three rolls, which Sarah twirls with satisfaction on her fingers, eying the cardboard treasure. Now she can laugh at the two staples of 6-year-old humour — bum and toot — when her dad makes a joke. She collapses in giggles on the bed.

She is squirmy and saucy. Squirmy and saucy until her mother, Leah, arrives with a small, squirming boy born Thursday.

It’s Sarah’s new brother, Matthew.

Leah places Matthew in Sarah’s arms. She speaks softly to her eldest daughter.

“What do you think? Do you like him? You can kiss him all you want, he’s all yours,” Leah says.

Sarah is the second family member to hold Matthew, after Leah. Mark was present at the birth, but he and Leah had promised Sarah she would be the second to hold him.

Matthew fusses as he leaves Leah’s arms to be placed into Sarah’s arms, but once there, he falls asleep. It’s amazing how newborns recognize kin.

“We’re a loud family,” says Leah, with a faint smile. She thinks Matthew recognizes their voices.

“Do you love him already?” she asks Sarah.

“Yes,” says Sarah, without looking up.

“It’s pretty quick,” says Leah, 36, a former nurse.

She opens the big cardboard folder. It is filled with hand-made cards from Sarah to her mother and to Matthew. “Mom Rocks the World,” reads one. “Baby power,” reads another. “Love, your big sis.”

“It’s a good day. A very good day,” Leah says, with deep satisfaction.

To add to their joy is the possibility that the stem cells from Matthew’s cord blood could be a match for Sarah, increasing the likelihood of a successful bone marrow transplant and more time for Sarah

Acute myeloid leukemia is a fast-progressing cancer that starts in the bone marrow and affects blood cells. Sarah was diagnosed in October 2012, after coming down with what her parents initially thought was strep throat.

She has undergone chemotherapy and blood and platelet transfusions.

Mark has been waiting to hold his son since he was born, but he holds back as Sarah sits mesmerized by her new brother. She isn’t squirming any more. She rubs her chin against his soft head.

Reluctantly, she gives him up to Mark, who cries when he finally holds Matthew for the first time. Then Mark refers to Matthew as ‘she’ instead of ‘he.’

“I can’t get used to the masculine gender,” says Mark, 38, laughing. “Him, he, his,” he says, trying to get used to it.

This is not the family’s first experience with grief. Leah lost a baby she had carried for more than eight months. The infant was stillborn.

Mark and Leah have a 2-year-old daughter at home in Thornhill, Elizabeth. She was tested, but was not a match for Sarah.

In February, nearly 250 people at Markham’s Milliken Mills High School, where Mark teaches, participated in a student-led stem cell and bone marrow donation drive, getting their cheeks swabbed and registering as potential donors.

Mark says he wishes more people knew that being tested for the stem cell and marrow network is simple and painless, and in most cases, donating is as simple as giving blood.

So far there has been no match for Sarah, whose story has been documented by her family on a Facebook page, Sarah’s Drive for Hope.

All hope now lies with Matthew, squirming in a onesie, oblivious and beloved, whatever the outcome.