Donna was engrossed in a book on the pyramids when the sound of a child running through the park caught her attention. She looked up just as a little girl skidded around a corner, her arms flailing and blonde pigtails swinging.

The girl tilted her head and looked at her for a long moment before a wide smile stretched across her face. She skipped over to the park bench and jumped up beside Donna.

"Hi! I'm Andi. Mummy told me to find someplace to sit so she could find me."

Donna raised an eyebrow. "And why does Mummy need to find you?"

Brown eyes danced with a mischievous spirit. "I wandered off," Andi replied matter-of-factly.

Donna closed her book. "Did you now?"

Andi nodded, sending her pigtails bobbing again. "Yep!" she said, popping the p. "Daddy says I get it from Mummy."

Right… the missing mummy and daddy. Donna glanced down the path, expecting to see a couple jogging after their errant child in short order. When no one came along, she looked back at the girl, who sat swinging her legs without a care in the world.

"Well, Andi," she said, "my name is Donna. Would you like help finding your mummy and daddy?"

"Nuh-uh." Andi crossed her arms over her chest. "Mummy said she'd be here soon. I just gotta stay in one place."

Donna nodded; she remembered her own parents giving her that instruction, if she ever got lost. "Do you know what your mummy and daddy are called?" she said, switching tactics.

Another toothy grin stretched across the girl's face. "My Daddy is the Doctor," she said proudly. "An' Mummy is Love."

Donna swallowed the sarcastic comment on the tip of her tongue—it wasn't Andi's fault that she'd never equate her own mum with love. "It's good that Mummy loves you, but do you know her name?" she said instead. "You're Andi, I'm Donna—what's Mummy called? What does Daddy call her?" she added.

A deep furrow appeared in her forehead, and Andi shook her head slowly. "Love is what Daddy calls her."

"Well, isn't that precious," Donna mumbled under her breath. It was, but it wouldn't help them find Andi's parents.

Then she mentally rewound everything Andi had said, and her eyes widened. "Hang on, did you say your daddy is the Doctor?"

Andi's frown disappeared, and she nodded eagerly. "Yeah!"

Donna didn't really think there could be more than one person running around just calling himself 'the Doctor,' but she double-checked, just in case. "Is he really tall and skinny, with a long brown coat?"

Andi clapped her hands together eagerly. "You've met Daddy!" she crowed. "I knew you had, when the lines around you were all curly like mine and Mummy's and Daddy's!"

Before Donna could ask what the hell that meant, she heard another set of footsteps racing down the path, and a moment later, a blonde woman appeared. Andi jumped off the bench and ran to her, and the woman swept her up into her arms and held her tight with her eyes closed.

"Oh God, baby! Don't do that to Mummy and Daddy!" she cried.

Another figure appeared on the path, this time one Donna recognised. The Doctor wrapped his arms around his wife and daughter and held them close.

After a long hug, Andi squirmed to be put down, and the Doctor crouched down in front of her. He could still feel his hearts racing, and the lingering fear made his voice sharp. "You know you aren't supposed to wander off, Andrea Suzette. What were you thinking?"

Andi pouted and scuffed her toe against the dirt. "I saw a dog, and I wanted to see if it would talk to me like K-9."

The Doctor sighed and shook his head—of course she did. K-9 adored Andi, calling her "Young Mistress" and following her around like… well, like a puppy. The two of them were inseparable.

He pressed a kiss to his daughter's forehead. "Next time, wait until Mummy and I are done explaining to the policeman why it's okay for us to leave the TARDIS in the middle of the park, okay? We can all go exploring together."

Andi groaned and reached for Rose's hand, like she always did when he scolded her. "But Daddy!" she whined. "If I hadn't wandered off, I wouldn't have found Donna! Look, her lines are squiggly. Does that mean she comes with us?"

The Doctor followed where Andi's chubby finger was pointing and he blinked when he saw a very familiar ginger woman sitting on the park bench. He stood up as Donna Noble walked over to them, a smirk on her face.

"Well, Spaceman, I see you found them. And I see you forgot that you were supposed to bring Rose here to visit me."

Oh. Right. The Doctor tugged on his ear, and Rose looked back and forth between the two of them. "Ah, yes. Sorry about that. We were a little busy with… well, life." He gestured from Rose to Donna. "Rose, this is Donna Noble. I met her just after…"

A lump formed in his throat, just like it always did. Even after almost four years, he still couldn't talk about Canary Wharf and Bad Wolf Bay without feeling the heartbreaking loss all over again.

Rose's eyes widened, and she stepped towards Donna, her hand held out in welcome, and Donna took it readily. "Thank you for helping him that day."

Now that she was right in front of them, the Doctor could see why Andi was so excited about Donna. Her timeline split and doubled back on itself as only a time traveller's would.

He bounced lightly on his toes, and both women looked back at him. "Do you see it, love?" he asked. "The timelines?"

Rose frowned, then looked at Donna again.

Donna shifted, and the skin around her mouth tightened. "What are you talking about, Martian?"

The Doctor sensed the moment Rose saw it. "What he means, Donna… is have you ever thought about doing a little travelling?"

Andi darted forward and stared up at Donna with her hands clasped behind her back. The Doctor bit back a smile as he pictured the pleading expression his daughter was probably giving Donna—he had yet to meet someone who could say no to her when she looked at them like that.

"Please, Donna?" she begged, swaying back and forth. "You hafta come with us. We can go anywhere in time and space!"

Donna looked from Andi up to the Doctor, and he nodded in response to the uncertainty on her face. "We'd love to have you join us, Donna."

After a brief pause, Donna nodded and Andi cheered and took her hand. "All right then," she said. "Time and space it is." Her lips curved up in a smirk. "Maybe if someone else travels with you and calls Rose by her actual name, your daughter won't think her name is Love."

The Doctor rolled his eyes as he reached for Rose's hand. He refused to be embarrassed by how much he loved his wife.

"I have a feeling that won't be the only thing Andi learns from you," he said drily.

Rose and Donna both burst out laughing, and after staring at the women with a confused little furrow between her eyebrows for a moment, Andi's giggles joined in. The Doctor reached for her and swung her up onto his shoulder, and then he led the way back to the TARDIS and on to their next adventure.