"Avada Kedavra!"
The glowing green jet of light shooting out of Severus's wand seemed to be moving in slow motion. For an instant, Severus and Dumbledore stared at each other as the spell moved, as if in slow motion, towards the older wizard's heart. Just before the spell hit him, Dumbledore gave Severus a very faint smile, and toppled out of sight, over the edge of the tower.
Severus struggled to conceal his horror at what he had just done. Quickly, he looked around at the Death Eaters surrounding him.
They all had the same look of shocked glee on their faces. Except Draco. He looked terrified, shocked, and angry all at the same time.
Severus hurriedly pulled himself together. Malfoy opened his mouth to speak, but Severus said, "Out of here, quickly." He grabbed Draco and hurried to the door. Out of the corner of his eye, he glimpsed two broomsticks hovering in mid air near the edge of the tower.
Potter…Potter was with him… Severus didn't stop to wonder where he'd gone, though, and continued down the stairs, pushing Draco in front of him. As they emerged from the spiral staircase, Severus saw Hermione Granger dueling a masked Death Eater, her face fierce and determined and her hair coming out of its bun. Ronald Weasley rushed past the staircase to her aid, throwing a hex over his shoulder at another masked Death Eater, which just missed its target.
Severus frowned, wondering where Potter was. It wasn't like him to be absent while his friends were in danger like this… He had no time to worry, though, because he had to get out of here, and quickly.
Dragging Draco down the corridor, dodging missed spells, and thinking quickly, Severus yelled,
"It's over, time to go!"
They rounded the corner and sped off down the next corridor. The full impact of the evening's terrible events hadn't hit him yet. He felt numb and devoid of emotion. Trying his hardest not to think about what had happened, Severus led Draco to the castle doors, and blasted them open in his hurry to leave before the Ministry came.
They raced down the cold stone steps, Severus's heart pounding. There was a roar of fury and Hagrid burst out of his house, aiming a spell at them with his umbrella, which apparently contained his broken wand.
Not now, not now… Severus thought impatiently. He shot a stunning spell at Hagrid, though he knew it wouldn't have much effect on him.
Running still faster, clutching a fistful of Draco's robes to make him keep up, Severus heard a horribly familiar voice in the distance.
" Impedimenta!"
Severus suppressed a groan. Could the circumstances get any worse? Trust Potter to hold them up when they so desperately needed to escape, for their good and his.
"Stupefy!" A jet of red light narrowly missed his head. Severus spun around, yelling,
"Run, Draco!"
Standing a ways away, breathing hard and glaring at him with such hatred it was startling, was Harry Potter. His robes were torn and singed in places.
"Cruc-"Severus blocked the Unforgivable Curse, sending Harry flying backwards. The sounds of Hagrid yelling, along with distant bangs and yells from the castle echoed across the grounds. Potter stood, shaking from rage, and started,
"Cruc-"Severus did not retaliate, but merely blocked the spell again.
"No Unforgivable Curses from you, Potter! You haven't got the nerve or the ability-"
"Incarc-" Severus blocked his attack yet again.
"Fight back!" screamed Potter, clearly frustrated at Severus's refusal to fire spells back at him.
"Fight back, you cowardly-" at those words, Severus's temper immediately flared.
"Coward, did you call me, Potter? Your father would never attack me unless it was four on one, what would you call him, I wonder?" He knew he was wasting time, but he didn't care.
"Stupe-" Severus vaguely wondered why Potter didn't cast the spells silently. Much as Severus hated to admit it, Potter was perfectly capable of casting spells using only his mind. It was a pity he couldn't do as well at Occlumency…
"Blocked again and again until you learn to keep your mouth shut and your mind closed, Potter!" Severus glanced over Potter's shoulder, where Hagrid's house had caught fire, and bellowed at the remaining Death Eaters,
"Now, come! It's time to be gone before the Ministry turns up-" Potter leapt at his chance-
"Impedi-" Before Severus could block the jinx, there was a jet of light,Potter let out a yell and fell to his knees, then to the ground, his face contorted from the pain.
A sudden burst of anger ripped through Severus, not at the young man on the ground screaming in pain, whose father had made his life miserable, but at the Death Eater who had been wreaking havoc on Hagrid's house, and who was now using the unforgivable Cruciatus Curse on Lily's son.
"No! Have you forgotten our orders? Potter belongs to the Dark Lord- we are to leave him! Go! Go!" The remaining Death Eaters departed, heading to the gates to Disapparate. There was another yell, so full of emotion: fury, rage, hatred, that Severus whirled back around to face Potter, who was now upright, his green eyes blazing-
"Sectum-" Severus repelled the curse. His curse. The curse he himself had invented, so many years ago. He could see Potter's face in the light from the fire. His jaw was set, his features determined and focused, and Severus knew what was coming.
"No, Potter!" Finally losing his usually carefully controlled temper, Severus blasted Potter backward. As he hit the ground some feet away, his wand flew out of his hand and landed in the grass. Severus approached Potter's defenseless form on the ground, gripping his wand tightly and trembling with such anger as he had not felt in a long time.
"You dare use my own spells against me, Potter? It was I who invented them- I, the Half- Blood Prince! And you'd turn my inventions on me, like your filthy father, would you? I don't think so-"
Potter dived for his fallen wand, which was lying a few feet away.
"No!" The wand flew out of sight as Severus shot a spell at it.
"Kill me, then." Potter glared up at him, not a trace of fear in his expression. "Kill me like you killed him, you coward-"
" DON'T CALL ME A COWARD!" Suddenly all the pain, confusion, fear, anger, and hate he'd been trying to shove to the back of his mind all day came rushing through him like a tidal wave. Without quite knowing what he was doing, Severus slashed at the air incoherently and hit Potter with something that wasn't really a spell, but magic that reflected all the uncontrollable anger he felt towards the boy.
There was a sound of wings overhead, and Severus felt a pair of enormous talons slashing at him. Looking up, he recognized the hippogriff, Buckbeak. Simultaneously, reality seemed to hit him, and, realizing how much time he had wasted arguing with Potter, he ran as hard as he could, toward the castle gate.
As he reached it, preparing himself to Disapparate, he turned to look back at the grounds, where he could make out Potter's dark figure searching frantically in the grass for his wand. Severus turned on the spot and vanished, leaving an enraged Buckbeak to circle the gates.