## Fidelity

### Chapter Text

Maybe this whole situation is like learning about imaginary numbers.

The first time Dave heard of them, he thought they were his teacher's idea of an April Fool's joke.

"Let's figure out the square root of negative twenty-five." Mrs. Buchanan wrote the figure on the whiteboard, but Dave didn’t copy it down. It was obviously a trick to see if anyone in the class was paying attention. Everything he had learned so far had proven that a negative number can't have a square root. Because whether you multiply a positive number by itself or a negative number by itself, the answer will always come out positive.

Except she kept going, parsing out the figure until she came to an answer: 5i.

Which was clearly something she’d just made up.

This,” she said, pointing to the i, “is the square root of negative one, and even though it's called the imaginary unit, it's real. It's as real as a positive number or a negative number.”

Dave highly doubted that, but he listened anyway. It’s not like he could text Azimio about this bullshit; Azimio didn’t know that Dave had ever made it past Algebra 1.

"Now, a lot of you probably thought that negative numbers weren't real when you first learned about them, since we can't count them on our fingers or with matchsticks. But now you use them all the time without questioning it. Math doesn’t make sense without them. Well, that’s how it is with imaginary numbers." Mrs. Buchanan drew a horizontal line on the board, jotting down zero in the middle and writing "1, 2, 3, 4 …" to the right of it and "-1, -2, -3, -4 …" to its left.

"I think about it this way," she said. "I picture positive and negative numbers on a one-dimensional line. But we all know that space has more than one dimension, right?" She drew a vertical line through the zero mark. "I think of imaginary numbers as being on this vertical line. They take our one-dimensional view of numbers and make it two-dimensional."

Dave shook his head in disbelief, but when she assigned their homework, he did the problems as instructed instead of writing, "This makes no fucking sense," all over his assignment, even though he was tempted to.

Over the weeks, though, as he worked with the numbers, they did start to make sense. Mrs. Buchanan would show them little tricks for using i to do trigonometry problems more quickly and still come to the same solutions. The imaginary unit was elegant and practical and – it seems strange to use the word truthful to describe a number, but that's what it was. It led to the right answers.

He was hooked.

*

On Thursday, when Dave arrives at Blaine's, it's Kurt who answers the door. He reaches for Dave's hand as soon as he crosses the threshold. Dave just stands there, staring at their interlaced hands, a weird amalgam of panic and joy flowing through him.

"Sorry," Kurt mumbles, pulling his hand away.

"No, I didn't mean –" Dave reaches to take Kurt's hand back, stopping just before he makes contact. The air between his fingertips and Kurt's skin is electric.

Dave's never initiated a touch with Kurt before – not this way, not in friendliness. He's always been so aware that he has no right. "Just," Dave says, but he doesn't know how to explain. His eyes flicker between Kurt's face and where their fingertips are almost touching. "Please."

Kurt closes the gap between them, wrapping his palm with Dave's and staring at where their fingers touch. “Thank you,” Kurt says with a satisfied grin.

Dave takes a deep breath as Kurt leads him to the kitchen. Blaine looks up at them from his homework, eyes stopping on their interlinked hands, and smiles with all the brightness of the afternoon sun.

*

Kurt holds Dave's hand again when they stand at the picture window looking for warblers, passing the binoculars back and forth. Dave's hand sweats a little less than it did the first two times Kurt took it this afternoon. He's able to focus more on the texture of Kurt's skin, the solid reality of Kurt's fingers.

Blaine gets up from the counter and plants a kiss to the back of Kurt's head. "Back in a minute.” Kurt keeps holding on to Dave's hand as Blaine turns out of the room, and the next time he passes the binoculars back to Dave he looks up at him like … well, it's something like the way Kurt looks at Blaine sometimes.

Dave forgets how to swallow. Forgets how to breathe. But his heart doesn't forget to beat. It's thumping harder than he remembers it ever doing on the football field.

Kurt squeezes Dave's hand and lets go, smiling shyly. "I guess we should study."

Or we could look at each other the rest of the afternoon. Dave doesn't say it, though. Everything's incredible enough as it is.

Dave is barely a sentence into his English homework when Blaine returns, ceremoniously slapping a book onto the counter in front of him. "Required reading," Blaine says.

Dave reads the title out loud. "The Ethical Slut?"

Kurt rolls his eyes. "Sweetheart, I wouldn't call it required reading. It's not like it’s Patti Lupone’s memoir."

“Well, that was phenomenal, but –” Blaine beams at Dave as if he's just transformed a pepper shaker into a real, live kitten. "This book is much more practical. It’s about, well some of it's about, um –" Blaine points at Dave and Kurt, then himself. "This?"

Kurt puts a hand on the cover and says coolly, "It's not only about being a slut," but his bright blush belies his tone.

Dave blushes, too. The world is not at all what he's believed.

* * *