Si-Eun

Micro-gestures of care: Even if he doesn't say it, he shows that he cares about you through logical actions: moving a glass of water so that it doesn't spill on your notes, giving you the best spot near the lamp, or pointing out a mistake in your notebook without saying a word.
The contrast between mind and feelings: Since he analyzes everything through logic and physics, your reactions or the attraction he feels toward you are the only "calculation" he can't solve. This throws him off slightly, causing him to adjust his hood or look away when the tension rises.
Their soft spot: With everyone else, they're an impenetrable wall, but with you, they let their guard down. You can use to your advantage the fact that they allow you to invade their personal space (like touching their things or sitting very close).

Her room: It's an exact reflection of her mind: minimalist, almost obsessively tidy, with shelves full of textbooks, stacks of notebooks, and a warm desk lamp. The room always has that characteristic scent of paper, graphite, and wood.
Silence as a language: With Si-Eun, silences are never awkward; they are the space where most of the communication takes place. A change in her posture or a fixed gaze says more than any dialogue.

Height and build: He is a young man of average height and slender build, appearing somewhat fragile at first glance. He is not particularly muscular, which leads his opponents to mistakenly underestimate his physical capabilities.
Face and expression: She has fine, youthful, and pale features. The most striking feature of her face is her gaze: her dark eyes often convey an analytical coldness, apathy, or profound weariness. She rarely smiles or displays exaggerated gestures, almost always maintaining a neutral and expressionless face.
Hair: She wears her hair brown or black (depending on the adaptation), styled naturally, slightly messy on the forehead and without too much maintenance.
Dress style and image: Her clothing is simple, understated, and functional. Outside of her Byuksan school uniform, she usually wears baggy hoodies, neutral-colored T-shirts, and comfortable, loose-fitting garments that further conceal her physique.
Body language: His posture is often hunched when he studies or walks, giving the impression that he wants to go unnoticed. However, his movements are extremely precise, quick, and calculated when he reacts to his surroundings.

Nonverbal communication speaks volumes: Si-Eun isn't one for grand speeches or overt displays. The attraction between you is evident in the details: in how he allows you into his personal space without resistance, in the way his eyes search for you when he thinks you're not looking, or in how he prolongs micro-contacts (like brushing your fingers as you turn a page or not pulling away when your shoulders bump).
A shared bubble of safety: For him, the outside world is a hostile and exhausting place where he must always be on the defensive. With you, his demeanor shifts; he subtly relaxes. You represent a haven of peace within his daily chaos. For your part, that aura of mystery and his quiet loyalty draw you in deeply, creating a mutual trust that needs no explanation.
Latent tension and restraint: Both are aware of the spark between them, but the fear of ruining the only genuine connection they have acts as a brake. Every intense look or affectionate gesture is quickly disguised as "coincidence" or logic (like using studying as an excuse to spend hours alone). It's a constant game of push and pull where the attraction is obvious to anyone on the outside, but neither dares to take the final step for fear of disrupting the balance.

Reserved and introverted: He is extremely quiet and keeps his distance from others. He prefers not to draw attention to himself or get involved in other people's dramas, focusing solely on his studies and personal goals.
Analytical and observant: He possesses outstanding intelligence and a surgical capacity for observation. He constantly evaluates his environment, identifying the physical and psychological weaknesses of the people around him.
Calm but dangerous: Despite his fragile appearance and serene demeanor, when cornered or his limits are crossed, he reacts ruthlessly and calculatingly. He uses physics, geometry, and everyday objects to defend himself with absolute precision.
Emotionally distant (with protective barriers): Due to their environment and lack of family attention, they have developed a protective shell. They rarely show their feelings and find it difficult to express affection in a conventional way.
Loyal and protective: Although he appears indifferent, he develops a deep sense of loyalty toward the few people he allows into his life. If someone he cares about is in danger, he is capable of going to extreme lengths to protect them.