"…and as we can see from the electron-withdrawing groups, the nucleophile will attack from the less hindered side, resulting in…"

The chalk squeaks against the blackboard. Someone in the back row coughs. The radiator under the window clicks and hums.

She tries to focus on the diagrams, on the arrows showing electron movement, but her mind keeps drifting. Is Cara still standing where she left her? Did she sit down? Did she

Stop. Focus. SN2 reactions. Backside attack. Inversion of stereochemistry.

Her hand moves across the borrowed paper, taking notes that she'll probably never look at again. The familiar rhythm of it helps, just slightly.

Her benchmate already read the chapter before the lecture and is bored bored bored.

She glances over at Vera's notes. The handwriting is shakier than usual, letters trailing off at weird angles. And is that a drop of water on the page?

She slides a crinkly half-full pack of tissue over without saying anything, miming a wipe of her nose.

She takes a tissue automatically, wipes at her face. When did she start crying again?

The professor drones on about leaving groups and transition states. The words wash over her like static. She should be taking notes. She should be paying attention. She should be

Back in her room. Making sure Cara hasn't done something stupid. Making sure she's still breathing.

Her pen creaks, switch-spring buckling under the pressure of her grip.

"Miss Hale."

The nasal voice cuts through her spiraling thoughts like a blade. She looks up, realizing the entire class is staring at her.

"Perhaps you'd like to share with us the major product of this reaction?"

He gestures to the board where a complex molecule waits, half-finished arrows pointing into the blankness of space.

It's not usual for lecturers to pay attention to their undergrads like this but, well. She does draw some attention to herself.

She stares at the board. The molecules swim in front of her eyes, carbons and hydrogens rearranging themselves into shapes that almost make sense.

"I… the nucleophile attacks from…"

The words stick in her throat. She knows this. She's known this since high school. But her brain feels like is wrapped in four layers of wool scarf, everything muffled and distant.

"The backside," she finally manages. "Inversion."

It's not a complete answer, but it's something.

"Correct, though I'd appreciate more attention to the specifics of the mechanism."

He turns back to the board, chalk in hand, and continues the lecture. The moment passes, but Vera can still feel eyes on her from around the room.

"…which brings us to the concept of neighboring group participation…"

She tries to sink lower in her seat. Her hands shake as she attempts to copy down the new diagrams, but the letters keep blurring together.

Neighboring group participation. Like how Cara's backlash participates with hers, creating new pathways, new possibilities for reaction. Like how touch creates conductance between two isolated systems. Mac charger skin fuzzies.

Stop thinking about her. Focus on chemistry. Focus on anything else.

The broken pen leaks ink across her palm.

"Just tired," she whispers. "Had a long night."

The understatement of the century. She turns back to the board, but the equations might as well be hieroglyphics now. All she can think about is Cara standing in her room, vacant-eyed and compliant, waiting for instructions that might never come.

What if she just. Forgets to come back?

Cara would sit there quietly until she died, probably. Vera ordered her to stay put and destroyed her phone - nobody who notices that she's missing would be able to find her in time.