When Kate came along, Alexis wasn't sure how she fit into her family anymore. Her father was creating a life with someone he loved, and for that Alexis was happy. But he went from being a father to a husband without ever having to be both at the same time. Alexis moved out around the same time Kate moved in, making it hard for them to establish a family.

Sometimes Kate would help Alexis study and she would feel she was warming up to the woman. Alexis was happy for her father and his new wife. She just didn't feel like she belonged in their family.

But when Kate left her father, Alexis felt more upset than she thought she would. This is why, two weeks into the separation, Alexis found herself banging on Kate's office door.

"Come in," her stepmother called.

"Kate," Alexis said, questioning herself. Why had she come down here again?

"Alexis," Kate seemed taken aback. "What are you doing here?

"You left us." Alexis let the words fall out of her mouth. "You may think you only left him, but you left us."

"Alexis, I'm…sorry. I didn't ever think..." Kate stumbled on her words. "It's not because I don't love your father. I'm doing it to protect him. Protect you."

"You have no idea what you've left behind." Alexis stomped out of the office, still unsure why Kate leaving bothered her so much.

When Kate returned, Alexis was skeptical. The night that she and her grandmother shared a drink with Kate, Alexis glared at her stepmother. "Promise you won't ever leave again."

"I won't, Alexis. I was wrong. I was so wrong. You father helped me see that." Kate met her eyes, a note of sincerity in them.

Alexis surprised herself with what she said next. "But even if something happens to him. Promise you won't leave us again."

A note of surprise appeared on Kate's face as she pulled Alexis into a hug. "I promise."

Alexis tried to stop the tears from falling from her eyes. She didn't know why Kate mattered to her so much. She was an adult. She didn't need another mother figure.

But the day that Lily was born changed everything. As her father was running around the hospital waiting room passing out "It's a Girl" candy bars to family and friends, Alexis sat in the room with Kate and held her baby sister. Lily bonded Kate and Alexis by blood. Her stepmother had given her the one gift she always wanted, a sister.

"I have a sister," she said through tears as she looked at the impossibly tiny child.

"You will be the best big sister in the world," Kate smiled.

Two years passed filled with brunches and coffee dates. Alexis spent more time at the loft than she had in years. She wanted to see Lily as much as possible. During that time, she and Kate spent hours talking about career paths and her love life. All of this led to the moment where she found herself calling Kate with the news before anyone else.

"Matt proposed. I'm getting married."

"Oh Alexis, I'm so excited for you. Let me get your dad."

"No…just a second, Kate. I was wondering if Lily would be my flower girl," Alexis asked.

"Of course, honey. She would love to be a flower girl for her big sister's wedding." She could practically hear Kate beaming over the line.

"One more thing…um…I was wondering. Would you take me dress shopping?" Alexis whispered, not being able to imagine anyone else helping her pick out the gown.

"I would be honored." Kate agreed.

Two years after that, Kate and Alexis were having coffee at the local coffee shop when Alexis blurted out.

"I'm late…like really late. I think I might be pregnant."

Kate pulled back in shock and whispered, "Um…me too."

Together they went to get pregnancy tests and found out the news together.

"I guess we better go tell our husbands," Kate said.

As the years went on, Kate occupied a place in her life that Alexis never thought anyone would. With her own absent mother and the loss of her grandmother a year ago, Alexis assumed she'd have to navigate motherhood alone. But Kate taught her how to be a mother. Even while wrangling her own three kids, she always had time to sit down with Alexis when she had a question about how to raise Noah. A year later, when Alexis had a miscarriage, Kate held her hand as she cried and listened as Alexis shared her fears about never having another child.

Three years after that, Kate held her granddaughter, excited that Alexis finally had the completed family she always wanted. She smiled at Kate holding little Mia and thought about how she never thought they would get to this place.

Kate went from being her dad's partner, to the third in a long line of wives, to Lily's mom. But Kate now occupied a very real and important part in Alexis' life as well. Kate was her best friend.