Many anime villains will regard their heroic counterparts begrudgingly. Often, the heroes are nothing more than an obstacle to their nefarious goals or a threat to the unjust status quo that has already been established.
However, some evildoers don't detest their heroic counterparts. On the contrary, they're absolutely fascinated by them. Whether it's because of love or as part of their plans, many antagonists are so violently obsessed with the hero that they'll even attack other villains for threatening them, conveying their own twisted form of admiration.
Warning: Spoilers ahead!
10 Hisoka Wants To Fight Gon When He's Reached His Full Potential (Hunter X Hunter)
Hisoka has been fascinated by Gon ever since encountering him in the Hunter Exam. He was so determined to watch him develop as a fighter that he even allowed him to keep his badge during the forest trial - much to the young boy's frustration.
The villain aided him again against Razor during the Greed Island arc, where he had an opportunity to gauge how his nemesis was coming along. Hisoka's sole interest is that Gon will be as challenging as possible in the fight where he intends to kill him.
9 Yukako Kidnapped Koichi In Order To "Improve" Him (JoJo's Bizarre Adventure)
Yukako was so obsessed with Koichi Hirose that she was willing to kidnap him after his grades began to slip. By employing Pavlovian conditioning, she had hoped to transform him into a man worthy of falling in love with.
Unfortunately for her, Koichi was not interested in her sadistic style of affection and escaped shortly after his abduction. Nonetheless, he would end up with her by the conclusion of Part 4. It is possible that this is due to the lingering effects of the "Cinderella" Stand.
8 Pain Was Obsessed With Taking Kurama From Naruto (Naruto)
Pain's ultimate goal was to collect all the Tailed Beasts in order to break the Five Nations. By forcing them through the suffering he felt, he intended to unite the world through mutual anguish.
After repeated failures by other Akatsuki members like Itachi and Kisame, Pain visited the Leaf village to personally draw Naruto out of hiding. Given that they were both mentored by the late Jiraiya, their impending battle was as compelling as it was emotionally charged. Ultimately, Naruto managed to impact the villain so profoundly that he resurrected Konoha at the cost of his own life.
7 Smoker Had A Grudge Against Luffy Since Loguetown (One Piece)
Smoker's career as a Marine was defined by his failures to capture Luffy. This was first seen in Loguetown, where his efforts were narrowly thwarted thanks to a surprise appearance by Monkey D. Dragon.
The two would cross paths repeatedly and sometimes even work together, such as in Alabasta and Punk Hazard. Nonetheless, Smoker proved his commitment to the World Government by attacking and nearly capturing Luffy during the battle for Marineford. Without Hancock's intervention, he might have even succeeded.
6 Toga Can't Stop Talking About Midoriya (My Hero Academia)
Ever since encountering him, Himiko Toga has displayed a palpable obsession with Midoriya. She spent as much time close to him as possible during the Provisional Licensing Exam and even took Uraraka's blood in hopes of a future encounter.
This was in spite of the fact that Midoriya has never even hinted at reciprocating her affection, especially since she is one of the League's most avidly sadistic members. Should she have reconsidered her career path, the two characters might have been more compatible.
5 Azula Made It Her Mission To Amend Zuko's Failures (Avatar)
When it was becoming evident that Zuko would never capture Aang and restore his status in the eyes of the Fire Nation, Ozai sent Azula as a replacement. She was significantly more ruthless and powerful, as illustrated through her mastery over lightning.
Azula was so doggedly obsessed with capturing Aang that she was willing to follow Appa for days at a time. In the end, she would have captured him if not for the unprecedented intervention of Uncle Iroh. After the Avatar was reported dead, she returned home to the Fire Nation as its greatest hero.
4 Ragyo Became Fascinated With Ryuko After Discovering What She Was (Kill La Kill)
Shortly after Ryuko was born, Ragyo performed an experiment on her in order to turn her into a human-life fiber hybrid. Assuming that the procedure had been a failure, she discarded her daughter and moved on to other endeavors.
When Ragyo ripped out Ryuko's heart at Honnoji Academy, the villainess rediscovered her long-lost descendant. Immediately, she went about corrupting the young woman and using her as a weapon to complete the life fiber takeover.
3 Gilles Was Obsessed With Winning Saber's Heart (Fate/Zero)
Gilles had an unhealthy obsession with Saber ever since the beginning of the Holy Grail War. Repeatedly referring to her as "Joan of Arc," his infatuation with the woman was only overshadowed by his appallingly sadistic tendencies.
Considering that his master was equally as maniacal, Gilles could indulge in his passion so long as he remained obedient. Fortunately, the other Servants conspired to defeat him before he could cause any more grave harm to the Grail War's participants or the many innocent bystanders caught in the crossfire.
2 Esdeath Fell In Love With Tatsumi The Moment She Saw Him (Akame Ga Kill!)
Due to her brutal and domineering tendencies, Esdeath was often a victim of her own loneliness. To remedy this, she hosted a tournament so that she could find a man worthy of being called her partner.
Tatsumi entered in order to gather intel for Night Raid and had no idea what he was up against. Since Esdeath identified the young man as an ideal combination of submissiveness and strength, she brought him to her chambers and announced that they would be together forever. She became so devoted to him that she was even willing to overlook his status as an enemy of the Empire.
1 Seto Kaiba Had A Serious Grudge Against Yugi (Yu-Gi-Oh!)
Seto Kaiba had a longstanding grudge against Yugi (or, more accurately, Yami Yugi). He loathed that, in spite of his superior resources and natural talent, he continued to be outsmarted by his puzzle-wielding rival.
Kaiba's vendetta became so obsessive that he even tried to flagrantly kill Yugi on a number of occasions. For example, he leveraged the boy's grandfather in order to force him and his friends through a series of deadly games, including a shootout with trained soldiers and a cage match with a serial killer named "The Chopman."