When Harry's eyes opened, he say he was in a sat up and looked around. Was this where his animal form came from? He racked his mind to try to remember what animals resided in swamps. Alligators, crocodiles, eels… his thoughts were interrupted by an ear shattering shriek that made his sweat roll backwards and his heart beat in reverse. He was frozen in fear as he felt the ground shake beneath his feet. Looking at the treeline, he saw trees falling. Something was coming. And, whatever it was, it was big.
After what seemed to be twenty minutes later, he saw it. It was tall, easily as tall as the Gryffindor Common Room. It had four legs, two arms, and two heads. It was pitch black, and looked like a man riding a horse, though the man had no legs, his torso fused to the horse. The arms were very long and brushed against the ground. The rider's head rolled about as if it's neck couldn't support it. There seemed to be bones showing, both heads showing their skulls - the rider's head having great horns - the arms, knees and elbow bones showing as well. The rider's chest showed a plate of bone. The horse's underside showed all of it's rib bones. The eyes seemed to glow crimson with fire. The horse's mane seemed to be made of smoke.
The beast stopped, the horse snorting smoke from it's nostrils. Harry watched, dumbfounded, waiting to see what would happen. For a couple minutes, the beast stood still. Then, one of the three fingers on it's left hand twitched and the bones cracked as the rider's body started to move in jerky movements. The body of the rider hunched over and it tilted its head to the sky, the rider opening it's too wide mouth, connected only by what seemed to be vines of shadow, and let out a ear piercing shriek. Harry covered his ears, wincing hard. His glasses shattered. Hopefully they only shattered in the vision and not in real life.
When he looked up, he saw two pairs of crimson eyes looking into his emerald ones. He paled. The rider was leaning on the neck of the stallion, and the stallion's head was tilted down, as if submitting. On instinct, he bowed. The beast did something unexpected. The rider lifted one of it's long arms and crossed it over it's chest, bowing it's head as the stallion bowed on one front leg, the other bent slightly. He kept eye contact the entire time. When they both stood in unison, the horse's head and the rider's head were both still bowed in submission. He hesitantly reached his hand out, looking away. He expected it to attack him. He was flinched slightly when he felt the stallion snort onto his hand. He was shocked when he felt the smooth skull of the beast under his hand. He looked back at it, the two eyes still staring into his. They had an understanding.
As Harry started to stroke the beast's muzzle, he saw it fade away, as if it were ashes being blown away in the wind. He felt powerful, even more so than before. He promptly collapsed like a puppet cut from his strings.