Following a life-changing fallout with the Joker, Harley Quinn finally starts fighting for good, hoping to change Gotham in the Harley Quinn series. Before then, she was unlikely to be a friend of Batman and a foe of the Joker. In this new life, Harley tries her best to navigate the ups and downs of being good, such as being framed for murder and seeking the help of Batwoman in #15.
Everyone is familiar with the friend-to-villain plot twist. But truly shocking (and sometimes confusing) twists are found when villains become friends. At once, a foe no one imagines turning good becomes an ally. Not only are these stories powerful, they reveal the dynamic of a character's personhood and morality, and keep readers excited for the next step in their journey.
Plastic Man
The stretchy embodiment of comedic relief, Plastic Man originally made his way through life as a criminal before becoming a hero. After gaining his new abilities, he remained active in crime rings as a conman to try to rid the streets of the crime he once participated in.
His criminal tenure was short-lived, and he eventually became one of the underrated, yet often appreciated heroes of the DC Comic universe. Unlike others in this list, Plastic Man never truly returns to villainy after becoming a friend of earth's most beloved heroes. At times, the Justice League—even Batman—expresses trust in him. He stands to be one of the most consistent friends of the Justice League.
Ravager
Rose Wilson, the daughter of notorious assassin Deathstroke, was trained by her father to be a dangerous killer—dangerous enough to stand a chance against Superman. Though following in her father's steps by opposing the Teen Titans, she has also been known to them time and again.
Ravager's friendship with the Titans led to good things, the best of which being a chance at love with Kid Devil. While Ravager's alternation between friend and foe has harmed her reputation, her keen abilities are a key asset to the Titans. ing the team proved that she is much more than a carbon copy of her father. She can make her own decisions, for love and for her own good, even if it means opposing Deathstroke.
Lex Luthor
Lex Luthor could be considered the anti-Tony Stark of the DC universe. Though he's known to stand against Superman to the bitter end, the New 52 comics offered a different approach. When the responsibility of Superman fell to his lap, he took it willfully. Perhaps his motivation to preserve the planet and some sense of the "greater good" made him a formidable Superman, though Clark Kent never fully trusted him.
Seeing one of the most powerful Superman villains dawn a silvery Superman-like suit delivered a shock factor like no other. Readers felt an eerie distrust in the new Superman. Lex Luthor's eventual transition from a feared genius to a somewhat humble hero is a fresh take on the historically austere character.
Killer Frost
Caitlin Snow (DC Comics' third Killer Frost) was relatively unknown until her debut in the CW's The Flash. While her arc in the DC Comics has mostly been villainous, some instances reveal that her heart may not yet be completely frozen.
Becoming a friend of the Justice League was pivotal in Snow's life. After abandoning a deal with Queen of Fables, she learns that she no longer has to view her powers as a curse, but rather a blessing. Clearly, Caitlin Snow's personal journey being Killer Frost was drastically changed only as she became a friend instead of a villain. Her maturity, reasonableness, and even peace of mind came when she decided to pursue good instead of fighting through every moment.
Two-Face
One of the most unhinged villains of the DC Comic universe has been able to break free from his persona on rare, seemingly impermanent occasions. In Detective Comics #1024, Batman manages to release Two-Face from his ties to villainy. This scene was emotional, as it recalled a hopefulness that Batman and Gotham once had in Dent.
It is refreshing to see the benevolent side of Mr. Dent time and again, though most are unsure how long he can manage to stifle his Two-Face persona. Given Two-Face and Batman's comic history, their companionship is a nostalgic reminder that Harvey Dent may yet break free from the grip of his life as Two-Face. Every benevolent appearance is another hint that Gotham could still be reformed and improved.
Sinestro
One of the most iconic villain-to-friend stories started out as a DC hero-to-villain story. However, in the New 52 comics, he is not so much seen as a heartless villain, but rather an anti-hero type who still has the good of the universe in mind. He even its that he considers Hal Jordan a friend.
Though he uses harsh means to bring about his own kind of justice, moments like these make the Jordan-Sinestro dynamic all the more complex and intriguing. It is expected that Sinestro spews disdain at Hal Jordan, so even the smallest moments of friendship have massive implications. Sinestro is proof that many villains are more complicated than meets the eye, and some even have the best interest at heart.
Harley Quinn
The young, promising Dr. Harleen Quinzel would likely be terrified of the Joker's wild, irrationally romantic love interest, "Puddin'." And yet, of all the versions of Harley Quinn that emerge, one of the most recent Harley Quinns seems to be closer with the Batman than ever before.
In the Harley Quinn #1 comic, she struggles to become a better person, trying to help instead of harm Gotham. She even has ties with Batman, working side-by-side to make the streets of Gotham better. Her turn to something closer to good shows that there might be brighter hope for Gotham yet; it also shows just how bad the Joker really was. He may have been mad enough to conjure Dr. Quinzel once more, something people haven't seen in ages.
Catwoman
Though Catwoman has not always been seen as a primary villain opposing Batman, she is a criminal and Batman is a crime fighter. One particular comic scene in 'Their Dark Designs' reveals that assets of the Wayne family were stolen, and Catwoman was involved.
And yet, even with this often unaddressed tension between them, Catwoman and Batman may share the most chemistry of any hero-villain pair in the comics. Over time, it becomes clear that Catwoman is more friend than foe to Batman, and she might think the same of him. Her companionship with him is important because it shows that Batman has sympathy for villains of pasts similar to his and that Selina Kyle is more than just a villain. In fact, they may see each other as lovers before they see themselves as opposites.
Red Hood
One of the most heart-wrenching stories in the DC universe is that of Jason Todd. Being killed by the Joker is bad enough, but worse is being resurrected by Ra's al Ghul only to find out that Batman has not sought to bring final justice to the Clown Prince of Crime. Because of this, he becomes an anti-hero and villain (to the Bat-Family, at least).
Frequently fighting Batman leads to a shaky relationship between the Dark Knight and the Red Hood, but his ultimate friendship with him becomes more evident as he learns to wrestle with his past and present. While Red Hood may not explicitly say, "I forgive you," the simple act of working alongside Batman has a massive impact on him. Red Hood's friendship with Batman shows that even the darkest events can't take away his love (or need) for the Bat family.
Carol Ferris (Star Sapphire)
Carol Ferris may not have been the first Violet Lantern, otherwise known as Star Sapphire, but she was one of the most powerful among the love-harnessing entourage. In Action Comics #601, Carol Ferris kills Katma Tui, John Stewart's wife. She collects a history of animosity against the Green Lanterns, proving to be a powerful enemy.
However, she eventually expels her past and becomes a respected ally with the Green Lantern Corps. Taming the power of love makes this villain-to-friend story extremely compelling. Not to mention it was one of the defining moments of John Stewart overcoming immense grief and anger. The mere fact that these enemies became friends is singlehandedly the clearest sign of the impact of good, willpower, and love in the world.