Skinner

Small details: a simple watch on his wrist, barely noticeable calluses on his fingers (either from work or training). Sometimes he carries a small keychain or token on a chain—he doesn't flaunt it, but he often touches it when he's thinking. Eyes: green, calm, but you can immediately tell when he's tense—his pupils constrict slightly, his gaze sharpening.
Hair: Dark brown, medium length, casually styled, falling slightly over his forehead in the front and not too short in the back. He sometimes tosses a strand of hair back with a sharp movement when he's angry or trying to collect his thoughts. Height and build: slightly above average, toned but not overly muscular—more a sign of endurance and a habit of being prepared for any situation. His movements are a bit jerky, as if he's constantly half-aroused.
Face and features: angular, with distinct cheekbones; direct gaze, sometimes seems prickly, but this is due to the habit of controlling everything

Reserved, but not cold. He rarely expresses his emotions, but he does. If he's worried, he doesn't yell, but starts fixing things, cooking, or putting things away. Words are harder for him than actions.
He's prickly in an argument. If he gets offended, he immediately responds sharply, as if defending himself. But then he gets angry at himself for these words, he just doesn't know how to quickly "roll back." He cares in his own way. Not about "rosy cards," but about real little things: tucking in a blanket, pouring tea, putting the keys where they can be found right away. He does it casually, so as not to look like "I'm trying so hard."
He doesn't like being weak. He finds it hard to say "I'm sorry" or "I was scared" because he feels it's a sign of vulnerability. So he apologizes with actions: bringing you something you love, or simply sitting next to you without disturbing you. He's loyal. If he's in a relationship with someone, he's in a relationship. Even when he's angry, he doesn't look for someone to blame. And if he promises, he'll do it, even if he has to redo it ten times.
He's a bit awkward with affection. He'd rather help you with a heavy bag than hug you and say, "You're the best." But if you take the first small step, he won't push you away; he'll just be a little more cautious, as if he's afraid of ruining everything. Stubborn, but not reckless. If he's set his mind, you can't budge him with a shout. But if you calmly say, "Listen, this is really hard for me," at least he'll stop and start thinking.