Katie and Brooke were friends. Then they were sisters. And then the honeymoon was over, for a while.

When Katie was in third grade, her adoptive family asked friends Barb and Mark Ylitalo to care for her as they faced the cancer diagnosis of a relative. The Ylitalos agreed, moving Katie into the bedroom, and life, of their biological daughter, Brooke, also a third-grader.

Barb, a pediatric oncology nurse, imagined instant bonding, late-night chats, shared clothes. Instead, Brooke fell apart.

"Sharing everything with Katie got to be too much for me," she said.

Barb and Mark, an insurance agent, shifted to Plan B: separate bedrooms, separate classrooms, separate summer camps. The relationship remained cool, with playground drama, fights around friends and shared distaste for the constant question: Are you actually sisters?

"Katie was a girly-girl, who changed her nail color every day," said 5-foot-10 Brooke, 18, a senior at Wayzata High School also studying at Bethel College.

"Brooke was a little messy," said 5-foot Katie, 17, a senior at Buffalo High School.

Once, they didn't speak for six weeks. In the fall of eighth grade, Barb and her mother, Jane Johnson, "Nana," took the girls to India for 16 days.

"I wanted Katie to know her roots," Barb said. "I felt strongly that Brooke should come along because, if I wasn't around in 10 years, someone needed to know where Katie is from."

It was a turning point. At the orphanage where Katie was taken from off the streets at 4, the girls jumped onto the swing set together. Barb cried.

"That was huge," she said. "Brooke understood then that we had to relive this. Katie wanted to share it. It was like they just decided to merge their worlds."

They rode on a camel and inside a bumpy three-wheeled taxi, called a Took Took, and navigated a dark, deserted alley to emerge at the Taj Mahal. The sisters returned home friends again.

"We don't even fight anymore," Katie said with a laugh.

The summer before 10th grade, Katie returned to her original adoptive family in Delano, grateful to be blessed with two families who love her. She spends weekends in Plymouth with the Ylitalos. Katie and Brooke shop, watch movies, talk about boys and school.

"Nana told me, 'One day, you're not going to imagine living without her,'" Brooke recalled.

Nana was right. Katie nods.

"I know I'll never lose her."

Duets is an occasional feature that celebrates unique relationships between two people.
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