Season 1, Episode 4: The Poisoned Chalice
"You disobeyed me," Uther said.
"Of course, I did," Arthur snapped, standing before his father still sweaty and dirty from his ride across the kingdom in search of the Mortaeus flower. "A man's life was a stake." He said nothing of Morgana having to offer the final push because well, if he was being honest, he hated that he couldn't come to the decision to save Merlin by himself.
"Do not let Merlin die because of something I did," Arthur continued. And he could still feel the Mortaeus flower pressing against his pocket, heavier than it should be. Merlin's only chance. If Arthur couldn't convince his father, Merlin would die. He couldn't-wouldn't let that happen.
"Why do you care so much?" his father answered. "The boy's just a servant." And Arthur knew it was supposed to mean something, servant. Hell, it had used to mean something to him, before Merlin. Before he'd turned Arthur's whole world upside down and side wise and taught him that servant were people to. Because Merlin had never been just his servant.
"He knew the danger he was putting himself in; he knew what would happen if he drank from that goblet," Arthur argued, though his father just rolled his eyes. "But he did it anyway. He saved my life." He pulled the Mortaeus flower from his pocket, holding it in front of his father's face.
"Gaius knows what to do with it. Put me in the stocks for a week—a month even. I don't care. Just make sure it gets to him. I'm begging you," Arthur said, and it wasn't something he was familiar with, begging. Certainly not like this, but he was doing it anyway, couldn't imagine not doing it.
His father took the flower in his hand, and for one brilliantly hopeful moment Arthur truly thought he'd help him. He thought his father would let Arthur save Merlin's life. And then Uther curled his fingers, crushing the delicate flower in his fist.
"No!" Arthur shouted, trying to lunge forward, but it was already too late. He could tell by the look in his father's eyes that his mind had been made up.
"You have to learn there's a right and a wrong way of doing things," Uther said, but Arthur couldn't find it in himself to look past his hand, to look past the crushed flower still barely sticking between his fingers. "I'll see you let out in a week." He said. "Then you can find yourself another servant," and he was turning and leaving the cell, dropping the flower as he went. As if it wasn't Merlin's last chance.
And Arthur felt something break in him as the door to his cell snapped shut.