"I didn't---" he gets the feeling that she's rolled her eyes.
The hand grips a little, and slides up, just an inch.
It's not his face he needs to have cooled by the night, now. 
Y/N finds one of his hands and eases it off his leg. Her fingers want to get between his.
He lets them.
Shyly, he grips back.
When Sherlock tries to meet her eyes, she finds her gaze back on the road. It remains there as, slowly, she raises their hands to her mouth.
"Y/N---?" he gasps as she presses a kiss to his knuckles. His heart thrums in his chest.
She's not stopping. Thank God she's not stopping.
She continues her trail, caressing each knuckle, all the way round until she reaches his wrist. 
When she reaches that sensitive patch of skin---his pulse fluttering below her lips---she parts them, and he wriggles in his seat.
He can't help it anymore, and turns his hand over, taking hers tenderly, gently, desperately---
When he draws it to his mouth, she smells of that perfume she wears---
And Jelly Babies. He kisses the soft, feminine row of her fingers, his jaw parting enough to taste her. 
They're dusted with powdered sugar and his lip twitches. 
When he slides one into his mouth, she hums, and he groans roughly. 
Before he knows what's happening, they've pulled into a layby, and Y/N shoves the gearstick into park.
Sherlock barley noticed; his kisses are working their way up her arm, his whole body leaning from his seat to hers. He leans a little more, wanting to bury his nose in her neck---
To his amazement, his disbelief, his absolute delight, she turns her head.
He captures her lips with a grateful moan. 

...

Sherlock blinks and his dream dribbles away like sweet tea poured down a sink. 
A lurid beam of sunlight is falling across his face---obnoxiously bright for the season. It's slicing into his eyelids, lighting them up pink, and he turns onto his back---with some difficulty. His brain feels like it's hardened into a dense, solid little marble and it's rolling around his skull, bumping into the backs of his eyeballs.
Cursing Lestrade, he presses his fists into his eyes---
Then blinks at them. 
His dream flashes hot as a lick of fire in his mind; Y/N drawing a chain of kisses along each ridge of bone, her hand sliding through his hair, calling him handsome, undressing him---
No.
Dressing him.
Helping him climb into pyjamas, dragging his faded old t-shirt over his head---
He knuckles his eyes again with a silent groan, so hard that lights explode, blossom, and dance.
They're still there when he lets his arms flop back down onto the duvet cover. 
No, they're coming from something else; a reflection.
Wincing as he turns his head, his mouth twitches with a soft smile.