At times, kissing is even more intimate than sex.
For Yuri, it is incredibly different from what he's used to. The lips of the girls in Zaphias are smooth and soft, tasting of strawberries and cherries. Their cheeks are chalky with powder, and their strong perfume always burns Yuri's nose. Even the girls in the lower district are the same, making their own perfumes in some sort of vain attempt to smell good, not realizing the strong scent is repugnant. The most irritating part about kissing girls is their tendency to pull away after only a few seconds. Yuri guesses it's shyness that causes this, and his decency makes him let them go and merely tap his foot in annoyance.
Flynn isn't anything like this.
His lips are chapped and often sunburnt from his work, and sometimes he is so aggressive that Yuri is the one who is forced to pull away first to catch his breath. Yuri feels a mix of satisfaction and frustration at these moments, angry at Flynn's skill with his tongue and his teeth and his lips when Yuri knows the straight-laced knight has less experience than he does.
But that doesn't change the rush he feels as Flynn's tongue flicks against his upper lip, a hand pressed against Yuri's bare chest and the other on the back of his head. The blonde isn't done when Yuri breaks away to take a breath, instead trailing kisses along his jawline and down his neck, sucking at the skin and leaving marks that Yuri knows will still be there the next day. Yuri feels his heartbeat quicken as his breath does, and he tugs at Flynn's hair to bring him back to his mouth for another proper kiss. The other man's chapped lips only serve to increase the feeling that Flynn is human, not some doll.
Flynn isn't a girl, but Yuri wouldn't have it any other way.