(Smile v.t./i.To make or have a facial expression indicating pleasure or amusement, with lips stretched and turning upwards at their ends; to express by smiling; to give (a smile) of a specified kind. ― n. an act of smiling; a smiling expression or aspect. ― smile on or at, to look encouragingly on; (of a circumstance etc.) to favour.)
Until the first time he was allowed into the city, the concept of 'smile' had remained a dictionary entry inside his head (he'd also had to annex the entries for 'pleasure' and 'amusement'), and the first time he'd seen what he assumed was a 'smile' he'd been stunned. Its giver was a middle-aged woman with greying hair and a tired face, reaching for her child in the street, and it made even her worn-out face look beautiful.
He'd stopped short in the middle of the street, fascinated at how such a little thing as stretching the lips and turning the corners up should be so stunning, when he realised that it was a similar expression to one Hojo wore sometimes, only without the maliciousness and cruelty. He'd decided then that if smiling could be twisted in such a manner it probably wasn't something he wanted to do, and it isn't until he faces Zack, who grins tentatively at him like he's the most fascinating creature he's ever seen that he wonders if maybe he's been missing out on something.
Zack is full of smiles and grins and smirks, and it takes him months to even begin to distinguish between each version, and even longer before he hesitantly tries to recognize what the differences are. Zack declares somewhere in the first tentative stages of 'friendship' (friend, n. person for whom one feels affection and respect; companion; helper; -ship amity; kindly feeling) that he's going to teach him to smile if it kills him. Sephiroth would have put money on it killing him in the beginning, but by the time Zack has managed to get him to see that what they really are is called friends he realises Zack is more a force of nature than anything, a hurricane in human form, tearing through and changing everything.
He begins to anticipate the day when Zack's lessons will finally sink in (he's learned not to doubt Zack's determination), which he realises after awhile is foolish, because this smiling business is harder than other people make it look. Zack is teaching him so many things, but to smile was the first goal, and he wants to achieve it – he's never liked losing (lose, v. losing, lost. 1. suffer loss; 2. get rid of; 3. fail to retain, find; 4. be bereaved of; 5. be defeated.)
He stands in front of the mirror and struggles to pinpoint which muscles are supposed to be manipulated to create a smile, and every attempt reflected back at him is skewed and awkward, less a smile than a grimace, something he knows too well. He'd give up, if only he didn't know Zack is determined to get him to smile, and the methods will become more outlandish and humiliating if he doesn't get the hang of it soon.
He studies other people's smiles with the intensity he usually reserves for new mission orders and sword techniques, and tries to find some common theme in them that he can latch on to and use as a starting point. Some people's smiles show teeth, and some are simple twists of the lips, and some are part of laughter (laughter, n. 1. the sound of laughing; 2. the activity of laughing; the manifestation of joy or mirth; of scorn.) and make the corners of their eyes crinkle at the edges. He discovers there are smiles known as 'genuine' smiles, involving movement of the zygomaticus major muscle near the mouth and the orbicularis oculi muscle near the eyes; 'genuine' because there are studies that suggest they are an involuntary response to a pure emotion (emotion, n. 1. A mental state that arises spontaneously rather than through conscious effort and is often accompanied by physiological changes; a feeling; 2. a state of mental agitation or disturbance; 3. the part of the consciousness that involves feeling; sensibility.)
He asks Zack eventually what this means, after long hours spent trying to figure it out and coming up with nothing, and Zack looks for a moment like he's about to be sick, though he can't think why – the cafeteria food is improving lately. "It means... a smile comes from the heart, y'know? It's... ah, shit, Seph--"
(nickname, n. a descriptive name adding to or replacing the actual name of a person, place or thing; a familiar or shortened form of a proper name.)
"You'll know, okay?"
The first time he feels the beginnings of a smile he is watching Zack tease a new recruit about his hair – chocobo! he yells, cackling madly, and the poor recruit is bright red with embarrassment and obviously wishing he could sink into the floor – and he feels something at the edges of his mouth, twitching. He suppresses it out of long practise, and never realises it might have been what he worked so hard to find, because it was so effortless.
The first time he really, truly smiles, is when he sees snow (snow, n. 1. precipitation falling from clouds in the form of ice crystals; 2. a layer of snowflakes (white crystals of frozen water) covering the ground. 3. v. fall as snow; "It was snowing all night") for the first time. It is on a mission to the Northern Continent, and Zack is scooping up the substance, pressing it between his hands, compacting it into a roughly spherical shape. He throws it at him with more accuracy than he's ever shown on the shooting range, and ice-cold water drips down his chest.
Zack's expression is expectant, and after a moment's confusion he realises Zack expects him to reciprocate the gesture, and so he does. When his first snowball smashes into Zack's face and makes him gasp and utter high squeals of mock-horror, he smiles, but Zack is so busy hysterically brushing the snow away he misses it, and neither of them realise what has just occurred.
Back in the city, he watches people smile from a distance, and thinks it unfair that they make it look so easy.
Zack isn't psychic; he doesn't know to tell him that the unfairness is actually that he finds it so hard.