Krista Sumner sighed in contentment, lounging in her home beneath the city streets. A giggle bubbled out as she watched Mikey attempt a 360 on his skateboard...and fall off.

Her brother was pretty funny when he wasn't trying.

"Krista, it's time for your lessons!" Donny called, and the brunette let out a sigh of boredom.

"Do I have to?" Krista whined, her blue eyes pouting.

"Yes," Donny replied, ever the responsible one. "You are still a minor, and minors are required by law to attend a scholarly venue to attain an education."

"Dude, she don't exist," Raph shouted out, taking the girl's side. "But why don't you teach her some math anyway?"

Krista heard the smile in his voice, even if he was punching a bag a room away.

"But math is boring," Krista groaned, looking at her purple masked brother. "Why do I need to learn it?"

"Well, in case you're trapped inside a video game and you need to break down the programming to escape," Donny replied, completely serious.

"That never happens," Krista grinned, then her laugh petered out when her older brother didn't let out a chuckle. "Does it?" She asked nervously.

Silence.

"Now, I know you're old enough to be in High School, but your math skills are still in the early middle school, late elementary range. We're going to focus on the basics today," Donatello continued, going into teacher mode.

"But we've been focusing on the basics!"

"Exactly," Donny replied smugly. "And you're finally grasping it. After today, I'll test you on the material and you can officially graduate to pre-algebra. Sound like a plan?"

"Can we read A Wrinkle In Time instead?" Krista countered, shuddering at the thought of a math test.

"How about you pass my test?" her brother replied ruefully, and with an over dramaticized sigh the brunette got up from her seat to come to the table Donny was placing math books on.

"Leo," Krista whined to her eldest brother as he passed her, sheathing his katanas.

"If I have to practice, you have to practice," Leo replied, ruffling her hair as he passed her.

"But you have the fun practice, I get math," Krista complained, trying to get at least one of her family members to understand that math and katana practice were not the same thing.

"Krista, you're procrastinating. Just get it over with," Donny told her, and with final groan she plopped herself down at the table.

From the balcony above, Master Splinter looked down at his children with a chuckle.

The beginning integration of Krista into their tight knit family had been complicated at first. And it wasn't because of his sons for once! No, Krista had been to nervous. She was still apprehensive about being seen, and in the beginning you would see more shadows than the young girl, and you would hear the sewers more frequently than you would even hear Krista whisper.

But, as time wore on, Krista became more used to the boys, and with a forceful push from the elder rat the girl was living in the light more than the shadows.

Now, the girl acted like a true teenager.

She could complain more than Mikey with his video games taken away, she could talk faster than him, and was just about as curious as the orange bandana'd boy. In short, she was becoming a true teenager.

And true to originality, Krista was also forced to take part in the human ritual of attending school.

"I think she's doing pretty good. You know, with a background like hers and all," Raphael commented, and Master Splinter smiled in pleasure. His son had sneaked up on him, a feat not usually accomplished. The boy was indeed going to rival his elder brother one day soon...

"Yes, her educational background is indeed lacking," Master Splinter nodded in agreement. "But she is like a sponge to water. She is soaking up much at a great rate. Hopefully, she will be able to know the material her peers are learning in the world above."

"I just think Donny's glad he has someone to teach," Raphael rolled his eyes, and the rat contained a small smile himself.

Donatello had once attempted to teach his three brothers with minimal success. Even when Master Splinter forced his three other children to learn the material, it was still a hard thing to do. Brothers don't always respect each other, especially when one of the four is trying to teach calculus.

"I believe you three learned more insults than actual information under Donatello's tutelage," Master Splinter replied ruefully.

"Eh," Raphael shrugged, and both winced as Krista's piercing voice drifted up.

"But X is NOT Y!"

"Exactly! That's what I've been trying to tell you!"

"I believe we will lose our hearing before she understands this math," Master Splinter muttered.

"I'm BAAAAACKKKK!" A voice called out cheerfully, making Master Splinter turn toward the entrance to their home.

"Miss Sumner," he called down to the woman.

"Mr. Hamato," Laura replied in that same honorific way.

"Mama!" Krista jumped up, using her mother as an excuse to not finish the problem.

"So close," Master Splinter heard his young son mutter in annoyance.

"Hey baby-doll, how was your day? Did you have fun with the boys?" the older Sumner ask, hugging her daughter.

"Yep, but Donny tried to make me do math," Krista frowned.

"Well, you never know. You might get stuck in a video game and need to dismantle its programming to get out," Laura Sumner said calmly.

"...That actually happens?!" Krista asked horrified.

"So, how has the math been going? Is she getting it?" Laura replied, turning to the tutor.

"She's progressed to pre-algebra."

"Wonderful! Progress, ah how sweet to hear!" Laura Sumner grinned, her eyes gleeful. "Now, you go finish your work."

"But-"

"No buts, sweetie pie. Besides, I need to talk to the black belt on the balcony," Krista's mom continued, pushing her daughter back toward the arithmetic and heading up to the rat. "How have you been, Splinter? My little angel's not making your fur turn gray, has she?"

"Between my sons and Krista, I am surprised I do not have gray patches," Master Splinter replied, and Laura laughed in agreement. "How was your work?"

"Eh, so-so. I got the painting back, I just cut in the process. If Interpol does a global search with my DNA, I'm dead," Laura sighed, annoyed.

The Sumner woman had decided, with much urging from the moral compass that was Master Splinter, to use her powers for good, and not evil. In a very Leverage-esque way, Laura was a Robin Hood to the misfortunate, bringing back stolen goods and valuables. She tended to go after big targets, pocketing some profit for herself.

Master Splinter was just glad she was staying out of trouble.

Sorta.

So, while the mother was away, the daughter would play.

Krista was left in Splinter's capable hands when her mother had to go play humanitarian, and the arrangement was loved by both sides. Splinter was happy to be able to spend time with his daughter, and Laura didn't have to worry about where the girl would go. Krista herself loved being able to go back into the sewers, her home at one point, even though her mother had bought the duo a little house in the world above.

And Donny just loved getting to teach somebody something.

"Interpol usually halts their search at continent's end, but I would advise you lie low for a few weeks."

"And do what? Hang down here with you guys?" Laura smiled.

"You and Krista are always welcome," Splinter replied.

"Ah, mi casa es su casa," Laura quipped.

"Of course, family is always welcome."