Mycroft loves the taste of sugar in John's mouth.
The sweet familiar flavour morphs when it comes into contact with him, some mysterious natural alchemy in John's body turning it richer, deeper, more nuanced. Mycroft discovered the phenomenon the day he 'kidnapped' John to La Cercle, kissing him over a caramel amaretto latte after one too many nervous flicks of John's tongue over his lips finally shattered his self-discipline.
Since then, it's become something of an obsession. His fetish, if you will. There exist a thousand different sugars in the world, from agave nectar to sugar cane, and a million desserts to be made with them, and Mycroft wants to know how every single one tastes when he licks it off John's tongue and smooth, smooth skin.
Sprawled on his stomach, John hums, all but purrs as Mycroft draws a wet line of saliva up the beckoning curve of John's spine. John tastes of chocolate there, for no reason at all that Mycroft can determine. "You haven't been painting yourself with candies before you come over?" he asks against the plane of a shoulder blade.
John laughs, high and soft. "I leave the painting up to you." The muscles of his back flex delightfully as he lifts himself to roll onto his back, eyes glinting up at Mycroft like amused, murky sapphires. "Mycroft Holmes, are you calling me sweet?"
"Mmm, no. I'm calling you delicious." He reaches over to the dish of Chambord sorbet on the bedside table. When Mycroft offers him the spoon, John obligingly allows him to slip it between his lips and out again. If the slow sensuous slide of it is reminiscent of other penetrative acts, well, it's a calorie-free indulgence on Mycroft's part.
John seals his lips around the spoon as it pulls out and smiles instead of swallowing. Mycroft can all but see the sorbet melting into thick syrupy streams; frosted raspberries and liqueur coating John's rich, warm interior. Who could possibly resist? Why should he try?
When Mycroft laps into him, John sighs luxuriously and opens up to be devoured.