Maybe it was a certain shuffle in their step when they were tired, or the twist of their lips when hearing about their friends' summers. It could be he picked up on a twitch that happened when they were touched, or could the soul truly be read through the eyes? The sharp edge to a laugh, the echo of a grimace in their smile, the way they held themselves, whether they looked others in the eye too much or too little. Whatever it was, he could pick them out of a crowd.
Minerva was of the opinion that he cheated and snuck into their minds.
Filius tried to stay out of the entire business, but when drunk at the Christmas meetings with the rest of the staff (though the potion master never attended), held fast to the option of eyes are the window to the soul. When asked as to why no one else could pick them out so easily, there was some talk of black holes and gravity from the Muggle-born wizard, confusing to the utmost.
Pomona thought he spotted some universal sign, something that he held as a trump card.
Aurora most often agreed with Minerva, along with Rolanda and Quiranus, the young Muggle Studies teacher. But sometimes, the astronomer would contemplate a kind of kindred-spirit theory with Sybil.
Kettleburn offered a mumbled opinion of animals that could sense each others' intentions, a more gut feeling than anything else.
Poppy insists that he merely watches and watches and watches, putting puzzle pieces together as they appear.
Septima—who has always been considered a little more eccentric than the rest of the staff (without being a con-artist)—will start mumbling probabilities and likelihoods of guesswork versus intuitive instinct and immediately return to her quarters and wall-to-wall chalkboards. No one knows if she ever figured it out, but it's almost a certainty that she did. Once the problem was resolved, she just forgot about it.
Dumbledore entertains himself with lemon drops and party favors while these drunken debates go on.
It's only when they're intoxicated that the teachers feel free enough to figure out how Severus Snape always knows the hurt children. The ones who get kicked around at home, or ignored so much they don't get that they matter, or get slapped only once and awhile, only when dad's drunk, and he doesn't mean it! The kids taking knives to their wrists, or ankles, or someplace where no one can see and laugh. Children who contemplate heights and ropes and potions like they're an option that keeps looking better. The students that keep drowning and falling and feeling like they're failing at everything and everybody.
Snape can pick them out of the crowd because he was one, once. There's nothing magical about it. He does watch and watch, and notice things. And there are signs of it everywhere to his seasoned eyes. He doesn't pity them, because that would mean he pities his younger self. And there is no room in his life for feeling sorry for himself. So maybe he doesn't ridicule them as he much as the others, and perhaps sometimes they get back their essays with fewer red marks.
A lot of the time, he says a word, cocks his eyebrow a certain way, or gives some other sign in the paranoid code only a few can recognize, and they react. Most of the time, the first reaction is shame. Sometimes, it's relief he sees on their faces, that someone knows. Then they keep reacting, hopping from one car to the next in a predictable train of emotions. Shame and relief turn into curiosity and nerves when nothing happens for awhile. Little, consistent signs over long stretches of time until they give up and talk to him. Some begin by being angry and accusatory, then get teary quickly. Others start out acting, probing, being innocently curious when a few well-placed jabs get them to turn as hard and dangerous to the touch as dry ice. A few of them are there because they just know he knows, and they need to confess their perceived sins.
Still, he's not nice about it. The professor continues to be his snarky, cruel, and sarcastic self, only offering them a choice. He could tell Dumbledore for them, or be as quiet as an empty grave. Never once has he broken that kind of confidence because —cruel as he can be—thoughtless will only describe him on the day he decides to kill himself. It would take a thoughtless person to slip inside these wrecked houses of children, past whispers of ghosts and too many mirrors, only to splinter a (maybe the) support beam while trying to scare off the vandals.
So he listens, comments, argues, discusses, and stays silent with these children, because they come back. Maybe it starts off with anger, or hope, or devastation, but every time, they've told him. Because as much as Severus Tobias Snape tries not to think about it, there is shrapnel in his own soul to coincide with theirs, and they recognize it eventually. One or two tried to fumble with the old signals—a glance that lasted too long, then eye contact, or a fumbling twist of words and searching eyes—but they get nothing for these efforts but a locked box.
Sometimes that's all you need, to know.
Snape isn't gentle, or forgiving, or pitying, but somehow he is the middle ground in a giant leap. Because he's never hit a student, and he's always paying attention, but he isn't condescending or nice or acting about anything. When he doesn't outright speak the truth, those so skilled in this mistrustful dance of words wrapped in a thin code (to keep reality from burning down around them) can always know what he really means.
Severus would deny to his dying day and far into the afterlife, but he is capable of great kindness.
Tell me what you think, please. I hope I kept it in-character, even if it's not a 'story' peice.