A/N please note that for my purposes, voldemort's wand is different from the one that was brother wand to harry's. only because otherwise, they wouldn't be able to fight.
"It would seem as if you've ran down the basics, Voldemort!"
"Indeed." A crooked half-smile played across the Dark Lord's face as he slowly withdrew his wand from the depths of his robes. Harry did the same, but many times faster.
"Expelliarmus!" They both yelled, with enough force to knock anyone over without the need of a jinx. Their wands both flew into the air, and exchanged bright yellow sparks, finally landing in the opposite duelist's hand. Voldemort released something of a hiss, and whispered,
"Our wands are of the same phoenix. We should find no problem…" Harry's eyes narrowed.
"Malfoy taught me this one- Serpensortia!" Another flash of light, and a snake dashed from the tip of Harry's wand.
"Then he was most definitely in Slytherin…Oppugno!" As the Dark Lord uttered this, the snake turned, and slithered towards Harry. Voldemort also hissed something in Parseltongue.
"Kill him, my brother!" Of course, Harry understood.
"I'm going to have fun with you…" he said in the same manner. "Densaugeo!" At this, the serpent's teeth immediately enlarged massively, and the serpent's now massive fangs weighed it down, so that it's head would not move.
"Fool! Engorgio!" the Lord said, this time in his own contorted English. The snake now grew to the proportions of his teeth. That is to say, large. Or as the spell goes, excessively large.
"Well-played! Evanesco!" And with this, the snake vanished. Harry's stamina was drooping madly, so he decided to stall. He was too smart to try talking, so he looked around the room, but did not drop his guard. Voldemort raised a mocking eyebrow. Harry suddenly realized where he was: a library! A big one too. And they were between two shelves. It seemed to be deserted. Harry backed away, into the large open room. Voldemort stood his ground.
"Bookcase-wasi!" Harry yelled as he pointed at the shelves now toppling down on the Dark Lord. But he was no squib.
"Reducto!" Voldemort said. The bookcases were quickly reduced to dust. But he had neglected that the rather heavy books were not part of the bookcase. And so they fell, rather, rained on the Lord. He fell in the torrent, with an honest thud. But Harry knew it wasn't over. So quickly he yelled with his full force,
"Petrificus Totalus!" The Dark Lord's limbs snapped together. Harry, now pointing at the bookcase, tried his luck,
"Reparo!" Surprisingly, the bookcase sprang back to its original form.
He now took all available precautions.
"Locomotor Mortis! Langlock! Levicorpus! Incarcerous!" Harry paused for a breath. He looked at the Dark Lord, dangling from an invisible rope, upside down.