Dementor

It was dark. No breeze, the forest was quiet and dense. he could only hear his own footsteps, making a crackling sound, crushing the dry foliage under his legs. That sound was the only he could hear, which was terrifying him. Every step forward was telling him that he is being followed. He could feel the andrenaline rush through his perspired body.
Stopping was not an option there. He moved on. His breathing, heavy.
He approached a lake. The water in the lake was black, which was just a reflection of the darkness there.There was no movement in the water. No sound. The seemed to be dead. His ears could hear his heartbeats. He now had lost the courage of taking another step and making a another disturbing crackling sound.
There, all of a sudden, he began to feel very cold. As if a wave of freezing air had passed. Everything else there also became ice cold in matter of seconds. He could the air he was exhaling. The surface of water in the lake had shockingly become ice. His spectacles, suddenly caught moisture. Everything there had became surprisingly cold.
And before he could make out what was going on there, he could feel some movements above him. Before he could look for what it was, it appeared. Over the lake. He could see it. His eyes wide open. His heart drumming under his chest. He had never seen a thing like this. It was a darkest of the black, hooded figure. It was floating over the frozen lake. It was like his deadliest nightmare in a physical form. The creature swiftly moved close to him.
To him the fear, the darkness, all seemed alive. As the dark figure closed to him, he could feel a force influencing over him. The creature was sucking his soul. He was hearing strange voices. Small children crying and moaning. Screaming of a girl. He was hit by a trance of his worst nightmares. He was seeing the worst things happened to him in his life. Bad memories, which he had buried deep in him, suddenly were more alive than him, haunting him. His most evil thoughts were attacking him. By now, there were two more creatures hovering above him. Sucking out his soul.
All of a sudden, he remembered something. A face. It was very blur. He tried more. Then, suddenly the face of his best friend became clear. And shockingly, even after the resistance of the trance he was in, that face made him smile, as it always does. He used this memory. He wasn't sure if it was the best but it was not bad at all. So, he let that memory fill him. Still resisting the creature, his trembling hands reached for the wand stuck back in his trouser. He removed the wand, held it straight at the figure. His heart beating very fast. He used the memory, with a great intensity he yelled, 'EXPECTO PATRONUM'.
A brightest of white light emerged from his wand. It had an ultimate intensity, filled with happiness. He suddenly realized that it was the right memory. That magical white light scared the hell out of that dementor(creature) and pushed it away with a jerk. All the bad things there were in seconds, vanquished !