Okay so Cardassians, right?
Except that trademark grayish-blue skintone with dark blue accenting is actually just the body's stress response when cold. And because they're cold ALL THE TIME out in space, no one realizes it's just a coloration shift (or just how badly they're freezing out here).
Then Julian "Personal Furnace" Bashir ends up staying over in Garak's bed one night after an impulsive (possibly slightly tipsy) kiss after a stressful week - then fumbling words spilled out from human lips and steadier cardassian hands did some exploring and clothes of questionable fashion got tossed and aside and eventually Julian found himself curled up with a refreshingly cool semi-reptilian body against his hot skin, his own body pumping out waves and waves of that good good humid heat to be trapped under layers of blankets for his chilly companion in return.
He has a minor panic when he wakes in the morning to find Garak's coloration completely shifted to desaturated jewel tones - skin a grayish peachy pink with deep teal green accents instead.
Garak hasn't seen his proper healthy skin tone since he left Cardassia Prime as a lad to join the Obsidian Order. He admires his face in the mirror a moment, before his mood suddenly turns dour and he spins around to pin a still calming down Julian (who thought he'd given Garak some kind of allergic reaction to his body chemistry or something) with an angry glare.
"My dear doctor, do you realize the entirety of my wardrobe has been tailored to a completely different complexion? Do you realize how difficult it's going to be to redesign clothing to complement both my returning sallow tones as the chill of the day sets back in throughout the evening AND my natural tones that will return each morning I wake up next toyou?"
"I... I'm sorry, Garak, I didn't know my body heat would... hang on," a goofy grin starts replacing his nervous lip biting. "'Each morning?' You, uh... you want to do this again? On the regular?"
"...you owe me fabric and labor costs for the past 30 years."