When she walked, the ground quaked and buildings shuddered. She was bursting with power, and she had no control. She was ruled by emotions and one wrong word could send you to your doom. No one knew her, but she never went unnoticed, her presence alone being eye-catching. There was magic at her fingertips, and power in her veins. She was merciless.
o - o - o
When he entered a room, no one noticed. Not unless he wanted them to. He could silence a room with a single look, and could disappear before you could blink. One wrong word, and he would make you disappear too. There was magic in his blood that he used to his advantage, because when you were invisible, how could you ever be blamed? He was cold.
o - o - o
When he spoke, it was to manipulate. He would move and use people like chess pieces and sacrifice them if deemed necessary. They didn't care about him, so he treated them the same. It was a game to him, and he would win. He was raised in a world full of magic, but nothing got him going like a good fight. Every risk was calculated. He was cunning.
In this story, they did not meet on the train. The boys didn't save her from a troll, she didn't save them from the dungeon. No, because this story is a little different.
In this version, the merciless, the cold, and the cunning met in the Alley. Knockturn Alley, of course. Because where else do you expect the merciless, the cold, and the cunning to be?