I really don't see either Snape or Voldemort teaching the other flight. Here is my headcanon for how both discovered it:
My headcanon regarding Snape and flight is that, inspired by seeing Lily fly as a kid, he tried in his teens to develop a method of flight. Levicorpus and Liberacorpus are some of the results of these experiments. He couldn't do it though, and eventually got stuck.
As an adult, Voldemort managed to develop his own method independently. Snape, using his previous experience, was able to find inspiration from Voldemort's method to manage to reverse engineer it, something that none of his other followers or people who witnessed it could do.
La Souffrance¹ ~ Tom Riddle
I. La Connaissance
The train whistled. The whiff of her hot breath only added to the hazy smoke outside. As the compartments trailed after one another, she pressed her nose onto the window. Squinting her eyes, she could trace the outlines of her mother's dark silhouette in the steam. She smiled, the red and heat of summer had slowly faded into the chill of early autumn. The naïve stones reveled in the damp of the light rain, unmindful of their prompt crumbling that awaited in the early nip of winter. A steady drizzle rhymed along the low screech of the wheels of the train, she tilted her head further as the darkened tiles of the platform slept out of her reach. There was a thump in front of her, she turned hastily.
There was a boy sitting with a slight hunch. He was sickly pale and there was a distant curious look in his eyes, she frowned, his eyes were a lifeless brown in the poor lighting of the train, the lack of color reminded her of the vague moving pictures her mother took clumsily, the slight shutter of the camera snapped in her head. He stared at her, she stared back.
The compartment shook with the blow of the wind but he sat still except for his straight black locks that bobbed up and down every once in a while, she took in his frame. He was scrawny and there was barely any flesh around him. There was a light hue of red around his cheeks, it made him look less of a corpse.
"First year?" She asked.
He paused. "Yes." He said carefully, eyes still staring at hers, his voice was obscure, the roar of a thunderstorm from another town, a slide of avalanche from the distant mountains, everything about him seemed to be fading out of existence. She nodded.
Perhaps she was too much of a child to notice the off-putting aura that the boy insisted on putting upon him, the bittersweet smile that he offered along to everyone. Perhaps she was too young to see the traces of blood that dripped a trail back to the very day he opened eyes upon this world, he was the offspring of a lie, a deception, a life-long agony that rested on his shoulders and perhaps that was why he would try to hurriedly straighten his misery crouch, she noticed later how he was as a branch through the course of the seasons, curling and uncurling under the weight of his past, if only she had known then.
She extended her hand.
He looked down at the curl of her fingers, later she would learn that he took time to ponder things that were seemingly new to him, at last he looked back up at her, the early morning sun stretched along to bathe in the scenery, and as the light washed the dim of the compartment away, she saw the gleam of mischief upon his skin and when he angled his jaw, the swirling wood of his eyes looked a tint of green.
A cold hand touched hers, she tore her eyes away from his and glanced at the bony fingers that gripped hers.
"Tom Riddle." He rasped as the low hum of drizzle rolled into a storm.
Yandere Tom Riddle/Lord Voldemort Headcanons
- You first meet Tom on the train to Hogwarts, both of you in your first year
- He finds it odd that you are speaking to him in the first place, other children always seemed to avoid him
- Tom sees you as bothersome at first, but you grow on him
- You become somewhat of a rival to him, both of you are incredibly smart. But to avoid Tom’s wrath you make sure to be just ‘dumb’ enough to not be smarter than Tom.
- He flirts with you.
- Any chance he gets to make you flustered or embarrassed in a crowd, he takes. He likes to see you squirm while you visibly show just how dumb he made you feel
- Once his obsession begins to take root you will be royally screwed.
- Suddenly you’re no longer a person to him, but a possession that he never wants to give up.
- You never have a moment alone (unless you are a Gryffindor￼ or Hufflepuff) he has people to watch you in the Ravenclaw rooms, and the girls Slytherin room and he can watch you himself if you are in the boys Slytherin.
- He will go with you to Hogsmeade to confess his ‘love' to you. If you accept and begin a romantic relationship with him, congrats you do not have to deal with an angry Tom.
-If you decline (rudely or politely) he has his minions find dirt on you or your family and then he uses it to make you pledge your loyalty to him. This also means you two will soon be the cutest couple in Hogwarts.
- This relationship is also kind of a scheme. Dumbledore and all the other faculty love you. They mostly adore him too, but both of you together couldn’t look better.
- Once the romantic relationship has started he gives you a set of rules.
- PDA is off-limits besides hand holding unless he initiates it.
- Your grades must be good.
- Your appearance must be clean.
- You cannot be rowdy or anything like that in public. Definitely no jokes or pranks.
- You must seem serious but also remain polite.
- No talking to certain people.
- If you are a fun-loving and bubbly person, your sudden behavior change will raise red flags for Dumbledore.
- If you are a quidditch player he insists you practice religiously (to keep up good impressions)
- He is not gentle with you in intimate moments. The only time he is gentle with you is when he’s kissing you on the cheek in front of people, but those are only given to remind you and those around you who you belong to.
- But when you are alone he is always rough, nibbling your lips until he tastes your blood in his mouth, tugging on your hair, or grabbing your arms or you in general with a tight uncomfortable grip
- Tom’s possessiveness is also displayed through the hugs he gives you. His grip is smothering and tight.
- But having Tom being utterly infatuated and obsessed with you isn’t all bad.
- He gets you the finest gifts (but don’t ask how he got the money)
- Tom makes sure your every need is met. You want a glass of water he will send someone to go get it for you, even if you try to decline and insist you want to do it (which will make Tom mad). You should not have to waste your time doing something so meaningless when your time could be better spent with him.
- Seriously, do not try to argue with him.
- After Hogwarts when he starts the wizarding war you are locked away in the Malfoy Manor under the imperious curse (if you resist)
- You change a lot of things for Lord Voldemort.
- Because of you he watches the whole prophecy and does not go to kill Harry. He ends up fully surviving and winning the war.
- After he has won the war if you did not resist him after Hogwarts and did not require to be put under the Imperious Curse you will be treated like a queen. Truly anything you want, Lord Voldemort will get it for you.
- But if you resisted and had to be put under the imperious curse, he will let the curse go, but your next days will be spent fawning over him. Telling him how great he is and how much you love him and belong to him. If you refuse and continue to misbehave Lord Voldemort will make your life miserable.
- Either way, he still drapes you in fine robes, because the Dark Lord’s lover cannot look ragged.
- The only human interaction you get besides Voldemort is Narcissa and Bellatrix.
- Bellatrix does not like you at all
- But Narcissa is your bestie, you two love having tea (or your preferred drink) together. While you gossip about the wizarding world.
- Narcissa keeps you updated on everything that happens in the world and in exchange you keep the Malfoy’s in Voldemort’s favor.
- Absolutely no hanging around other men! If you are reported to speak to a man then the man and his family are dead as soon as Voldemort finds out.
-Voldemort’s obsession and possessiveness of you never goes away. You’re only his forever until the end of time.
(Gif found on We Heart It)