There are so many fanfiction authors out there that it's difficult to single out ones for this specific combination. However, some authors who are known for their creative crossovers might be worth exploring. For example, an author who has written other successful crossovers between different TV shows and book series could potentially be the one to write about Harry Potter and Elena Gilbert. The lemon aspect might be added by an author who is not afraid to explore the more romantic and passionate sides of relationships in their writing. You can search for such authors by looking at the most - read and highly - rated fanfictions in the crossover category.
Honestly, finding an author dedicated solely to Harry Potter, Elena Gilbert, and Lemon fanfiction is a bit of a long shot. But there are authors who are into crossovers and who might dabble in this combination. You could start by looking at the works of authors who have a large following in the fanfiction community. They are more likely to take risks and try out different combinations like this. Look for those who are known for their detailed characterizations and engaging plotlines. If they have a knack for writing about relationships, they might be the ones to add the lemon element when combining Harry Potter and Elena Gilbert in a story.
Chapter 298, "Hou Jing Surrenders, White Abyss Falls, Zhaoyang Changes Its Banner (Part 4)", is the clearest early answer because it turns Peng Bo's situation into a concrete plot event. It opens with I am Wu Ningyuan, I am willing to surrender, please show mercy." Chen... and closes on Suddenly, two unknown objects were thrown next to Xia Hong, crashing....
Chapter 281, "Yang Li's Suppressed Anger and Hatred (Part 3)", is the clearest early answer because it turns Great Xia's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Li Yuanqing and Yang Gan's surveillance and suppression of them had... and follows through with Their homes had been intruded upon by many people, with their....
Chapter 291, "Infighting in Long Mountain, Li Tiancheng's Caution", is the clearest early answer because the buildup finally cashes out in a real clash. A useful checkpoint is the way the scene starts with Li Xuanping was not only the eldest son of Li Tiancheng, but also the... and follows through with She had already secretly discussed with the second uncle Li Tiancheng....
Chapter 334, "Hanqiong's Seven Divisions, Moao Mountain, Beishuo Revisited 4", is the clearest early answer because it turns Lu Yang's situation into a concrete plot event. It opens with Lu Dong looked at the thirty members of the Steel Mane Team and... and closes on We should be heading north now!" Wang Tao, with a good sense of....
Chapter 338, "Rapid Progress, Martial Arts Skills, Dual-Faceted Eastern Expansion, Dormancy Period", is the clearest early answer because the violence around Xia Hong becomes final instead of hypothetical. The setup is Fifty-four鬃, not even a month, twenty-three days, and I even spent..., but the pressure keeps building through The actual time spent cultivating should only be twenty days, and in....
Chapter 304, "The Defeated Longyou Army, Xia Army Cannot Escape, Holy Tripod", is the clearest early answer because Cold Resistance Level gets a payoff that changes the stakes. The chapter turns that into something concrete by moving from The people's expressions, which were originally somewhat dispirited,... to Long Mountain originally had just over 70,000 people..
Chapter 148, "None are Normal", is the clearest early answer because it turns Du Qinglian's situation into a concrete plot event. It opens with Exiting the cottage, Director Sun picked up the phone. and closes on Just as Jiang Li put down her chopsticks, she received the call from....
Chapter 310, "The Leader Is Still the Best, The Consequences of Losing the Bet", is the clearest early answer because it turns Xia Hong's situation into a concrete plot event. The chapter turns that into something concrete by moving from Li Tiancheng tightly closed his eyes, his face filled with pain,... to Why did her second uncle not let her lead the Li Family disciples to....
Chapter 284, "Astounding Training Results, The Voyeur", is the clearest early answer because it turns Horizontal Blade Camps's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Roar!" The remaining seventy or so Cold Beasts still charged towards... and follows through with Unlike the other nine camps equipped only with Mo Blades and....
Chapter 284, "Astounding Training Results, The Voyeur", is the clearest early answer because it turns Horizontal Blade Camp's situation into a concrete plot event. The chapter turns that into something concrete by moving from Roar!" The remaining seventy or so Cold Beasts still charged towards... to Not only did they hold, but they even began to fight back.. What makes it stick is that the chapter closes with Liu Yuan led a hundred elite Scouts jumping down from the tree.