Um
I don't particularly know why this is a thing I thought would be socially acceptable
But I have mild synesthesia, and have always found Terezi interesting because I can associate with that part of her character; the abstraction of the senses. It's pretty fun to toy around with, and she's a pretty fun character in general, and then Dave snuck his way in here, and fanfiction happened. The end.
Dave was never completely at ease about your licking habit. When you first met, nine years old and having just moved into the apartment across from his, you licked his face before you spoke to him. Itty-bitty Strider had an uncharacteristically uncool moment after that. You had thought it was odd, and then you thought it was cute so you gave him a pat on the head before turning back into your own apartment to aid in the unpacking process. After that, he didn't bother to learn your name, instead calling you the Tongue Girl. That just about tickled you pink.
You got him used to the licking, of course. When the two of you started dating, all the way back in freshman year, you had made it clear to him that he was going have to deal with your habit. He had managed it through your prior years of friendship, but you had a feeling that as a couple…well, couples use tongues more than friends, do they not?
Soon enough, he went from being okay with your licking to even liking it, and not even in an ironic way. When other kids snickered at you, a troll and a human walking down the hall hand in hand, they would make crude jibes about your now school-wide infamous tongue. Dave would shrug it off, letting slip a vague statement about 'how very talented she is' and that shut the kids up, and made them all blush. You'd cackle and run your tongue along his jaw lightly; an explosion in your mouth like an inhalation of icy air, tickling your throat. Everybody present was thoroughly traumatized yet green about the gills with jealousy at the same time. People rarely bothered you, instead accepting that, yeah, Cool Kid Strider's girl was a little batshit around the edges, but there really wasn't a thing to do about that.
Blindness does occasionally get to you, though. You realize that nobody on Earth sees the way you do, constructing your other senses into a most brilliant pair of makeshift eyes. You feel lucky that you see your own special way, and it makes you smile when Dave offers casual comments about how normal eyesight is just too mainstream for you—after which you always do your best impression of Eridan. Still, you remember being able to see, before your accident. Seeing was pretty fun. You do sort of prefer tasting the world. Tasting is fun.
Seeing with your eyes, though…you don't want to, but every so often you let yourself get a little frumpy about it. But that's where Dave comes in.
You never outright say when you're upset about anything, relying on others to pick up the subtle changes about you. Dave has a habit of being emotionally ignorant at times, but he can almost always pick up when you're feeling sore about your lack of sight. Probably because at those times you always find your way into his apartment, and onto his lap, and then your tongue finds its place all over. He's used to it, of course. He barely notices anymore.
All tastes are spectacular to you, but you have a special place for his. His pale skin is like the aforementioned swoosh of glacial air, and his fingernails are peaches. His hair, even if you are not fond of the texture and he doesn't really like having his hair slobbered on, is still sometimes visited, just for that unique arctic sun flavor. He's a cold-tasting person; each person has their own color-palate as you call it, a general guideline that their flavors follow. His is aloof and cool, which is sort of fitting you guess. You like the cold, however. It's refreshing, since most people have warmer, mustier tastes.
Sometimes he reads one of his ridiculous magazines as you go about your business, and sometimes he sips a drink slowly. Sometimes, like right now, he winds his fingers in your hair, smiling faintly as your tongue has a hay-day. You lick his glasses and shiver at the explosion of black licorice. He grumbles and takes his glasses off, half-heartedly calling you out on being slightly gross. You giggle and run the very tip of your tongue along the waterline on his bottom eyelid; salty and fresh.
"Terezi Pyrope, you are pretty fucking weird." He tells you in an oddly affectionate way; he almost never gives a direct 'I love you'. You kiss him on the lips and it's sweet rosewater, an almost embarrassingly delicate taste for such a guy as him. You've never told him about it, liking to keep that one taste your secret.
"I know, right?"