Cosima loved her job. Once she had gotten her PhD, the University of Minnesota itself had offered her a place within their teaching staff, asking her to teach the module on Evolution and Population Genetics. The pay was great, so were the hours, she got to use the lab whenever she wanted, and she got to keep the apartment next to the University which she had grown fond of. Besides, she wasn't so lonely anymore, now that Delphine had moved in with her a while before graduation.

She was in the lab with her students one day, showing them the different preserved specimens they had in their storage. They were first years, barely out of high school and as fascinated with the world as she remembered herself being at the age of eighteen. She had sat them all down around her and was talking as slow as she could muster, giving them time to take down all she was saying.

"You can clearly see, from the diagrams I gave you last week, and from what I'm showing you in the glass case here…" she indicated at the case, pointing at the butterfly inside it (Heliconius charithonia, Zebra Longwing), "that insects, like any other organism, will adapt to their surroundings. Last week we saw that butterflies got smaller and smaller the more time passed, changed their colours according to their environments. And all this occurs from…?" she trailed off, waving a hand randomly at her circle of students and landing on a fair-haired boy sitting in front of her.

He spluttered out "Mutations, leading to Natural Selection," and she nodded, giving him her winning smile.

"Yes, good. There's different kinds of selection, we mentioned them last week. You!" She pointed to a girl with neon pink hair, who jumped up, startled, staring at her with big doe eyes. "Give me one example of such selection."

"Directional selection in the…uh…moths in England in the Industrial Revolution?"

Cosima nodded, snapping her fingers. "Yes, exactly. Selection is a wonderful thing. It will always adapt to the surroundings, to what it really needs to survive. That's what we mean by Survival of the Fittest. Nature is always looking out for us, even if means that we have to make a few sacrifices. But there's a reason animals have been around longer than humans, and always will be."

A bell rang across the class, breaking her speech. She closed her eyes and waved her hands at the wrists, shooing her students away. "Go! Go forth! And for next week I want you to write me a three hundred word essay on the different types of selection. Make it a good one!"

They left her alone in the lab to clean up the specimens she had brought out of display, putting the skeletons of animals back in their place and the gel-encased crabs and snakes back into the cabinet, humming softly to herself as she did.

"You sure know how to keep a class interested."

She looked up at the new voice, and smiled at the other teacher in the lab, a woman with neat blonde hair tied back in a ponytail, staring at her with intent as she strode across the lab towards her.

"Yeah, I remember what it was like to be their age. And clueless."

The other woman gave a breathy laugh and stopped right in front of her, crossing her arms over her chest and cocking her head to the side. "What's your name?"

"Cosima Niehaus, I started teaching this year."

"Oh. I'm Natasha Clover, I teach Oncology, started about two years ago."

"Oh, cool," Cosima nodded, extending her hand for a hand shake. Natasha accepted it, and with unnecessary force, pulled Cosima towards her. Cosima noticed that she was just that much taller than her, and she gulped when she realized that the proximity of their bodies was something very close to…well…not-really-that-friendly-anymore.

"How do you like teaching here?"

"It's…it's pretty cool," she stammered, blushing at the neck. Oh God, why was she doing that?! She had a girlfriend who worked in the other lab, she wasn't possibly feeling any sort of attraction to this woman, was she? She felt sixteen again…

"Cosima?"

She turned around and smiled at Delphine, who had just walked into the lab with a small carton bag of what Cosima assumed to be the lunch they would share at this hour. She tore her hand away from Natasha's, walking over to the French woman and standing on her tiptoes to meet her lips with her own, wrapping her arms around Delphine's waist in the same breath. "Hey, gorgeous."

"Who is this?" Delphine asked, narrowing her eyes at Natasha and pushing Cosima away gently to look at her.

"Uh, Natasha Clover, fellow lecturer. I was just introducing myself."

"Yes, hello Miss Clover. I'm Delphine Cormier, Head of the Immunology Department – newly appointed – and you," she said, tapping Natasha on the chest as she said the last word, fiercely squaring up to her, "were flirting with my girlfriend."

"I, uh, didn't know," Natasha offered lamely, her turn to blush as she backed away, moving back to where she had been sitting before in the lab, grabbing her bag and leaving in a hurry. Cosima looked over at Delphine, surprise etched on her face and a small smirk playing at the edge of her lips.

"Delphine, I've never seen this side of you before…" she joked, walking up to her and grabbing her hand in hers, tugging slightly. Before she could react, Delphine had grabbed her with one arm around her waist, the other hand cupping the back of her head, and pulling her into a heated kiss, seizing any more jokes on the tip of her tongue. When she pulled away, lips still a breath away from hers, she pushed their foreheads together and whispered hotly against Cosima's skin, "Don't you ever, ever, let anyone take you away from me. Understand?"

"I…"

"Understand?"

Cosima nodded, and closed the distance between them with a small kiss, hoping to calm Delphine down somewhat. "OK. I won't."

"Thank you."

"I didn't peg you for the jealous type…"

"I may surprise you yet," Delphine smirked, and Cosima pulled her into a hug before whispering "Come on, let's go have lunch."