One great 'Harry Potter Grindelwald Voldemort' fanfic is 'The Dark Alliances'. It delves into the possible interactions between Grindelwald and Voldemort that were not fully explored in the original series. It shows how their dark magic ideologies might have collided or united in a different way.
Some fanfics focus on the power dynamics between Grindelwald and Voldemort. Since both are extremely powerful dark wizards, exploring who is more powerful or how they could work together is unique. For example, in some fanfics, Grindelwald tries to manipulate Voldemort for his own gain.
One great Snape vs Voldemort fanfiction is 'The Dark Mark's Secret'. It delves into Snape's complex relationship with Voldemort. Snape is constantly in a precarious position, having to play the double agent. The story shows how he uses his wits against Voldemort's brute power. Another one is 'Snape's Hidden Alliances'. It focuses on how Snape manages to outmaneuver Voldemort in some crucial situations. The characterizations are really well - done in both of these, making them engaging reads.
The main thing that makes Snape vs Voldemort fanfiction interesting is the contrast between the two characters. Snape is complex, with his own motives and a hidden side. Voldemort is pure evil. So when they interact, there are always mind games and power plays. For example, Snape has to constantly deceive Voldemort, and the tension this creates is exciting.
Well, in a fanfiction, a plotline could be that Percy Jackson is on a quest and somehow crosses paths with Voldemort. Voldemort senses Percy's power and wants to study it. Percy, not knowing much about the wizarding world, initially mistakes Voldemort for just another monster. As they interact more, they realize that their worlds are more intertwined than they thought. Another plot could involve a powerful artifact that both of them are after. The artifact has the power to change the balance of both their worlds. So they are in a race against each other to get it, but along the way, they start to understand each other's motives and might even consider working together to keep the artifact out of the wrong hands.
Their interaction would be intense. Merlin, being from a different era and having a different view of magic, would likely be appalled by Voldemort's use of dark magic. Voldemort, on the other hand, would probably see Merlin as a threat to his power. Merlin might try to reason with Voldemort at first, but when he realizes that Voldemort is beyond redemption, he would use his magic to stop him.
Hermione is often a very popular character. She's known for her intelligence and resourcefulness, and in fanfiction, she might come up with new spells or strategies to help Harry in his fight against Voldemort.
One interesting plotline could be an alternate universe where Harry and Voldemort have to team up against a greater evil. This flips the traditional dynamic on its head.
Merlin is from a time when magic was perhaps more primal and less restricted. He has an intuitive understanding of magic that Voldemort, who is more about power - hungry and dark magic, might not fully comprehend. Merlin has been known to perform feats like creating powerful illusions and controlling the elements. Voldemort's main strength lies in the Unforgivable Curses and his ability to create Horcruxes. But in a direct magical duel, Merlin could use his magic to disrupt Voldemort's attacks. For example, he could use his knowledge of nature magic to counter Voldemort's dark spells. Also, Merlin's ability to blend into his surroundings and his quick thinking would make it difficult for Voldemort to land a decisive blow.
Percy would win. His powers are based on the elements which are a fundamental force. Voldemort's magic, while powerful, is limited to the wizarding world's rules. Percy can call upon water from anywhere, and that's a huge advantage.