Draco felt a shock that shuddered through him when Harry's mind closed. If he were a better Legilimens, he might have managed to extricate himself then, but instead he found himself entwined, Harry pushing back against him. The mental shove was rougher than anything he had ever experienced, simple pure raw power rather than the subtle touch he was used to. Draco tried to keep his walls in place, tried to push the memories out of the way, but he felt the glass jar shatter abruptly, releasing a piece of his life for Harry to see.
Draco knelt on the cold stone floor, gasping for breath, shivering in the aftermath of the crucio Bellatrix had just released him from. His mother's voice came from far off, begging for his life to be saved, and Bellatrix's response came in soft singsong tones, silk and steel as she promised to satisfy both Narcissa and her Lord and Master. As she promised that he would live, but that he would wish he were dead.
And he heard his mother leave.
The pain came again, brighter and sharper than before, keeping him just this side of coherent. She spoke the entire time, telling him how wonderful her Lord was, and how he must obey, and never fail again. After a time, she found her stride, and he felt the way she drew her wand across his back. One stripe from his right shoulder to just below his left arm, and another corresponding one drawn from the left side of his neck across his spine to his right hip. Over and over again, marking him deeper and deeper, until he had to scream from it.
It thrilled her, that sound, and so he did it again. He used it, put everything he had into the way he caved to her will. He let her cause him pain in the hopes that it would end soon.
He wrapped himself in that pain, relying on the way it went on and on, twisting it up and locking it away until his screams became show. He is your Lord and Master, she whispered, and he repeated it with her, again and again. He took his fear of his aunt, his sheer terror, and he shoved it aside. He took his horror at the idea that this was what was in his blood, what he would become, and he shoved it aside. And he repeated her mantra again and again until he made himself pretend that he believed it.
She sought to break him, and he let her, screaming again and again, until he rewrote his mind in her image. And he hated it.
Draco jerked back from Harry physically, stumbling to the side, around the foot of the bed, breathing hard as he wrested their minds apart. "Don't you ever do that again," he growled.