The Vampire Diaries franchise came to an end when Legacies was canceled this past May. While there have been discussions of new TVD spinoffs, the cancelation hopefully helped the showrunners learn which aspects of The Vampire Diaries were so compelling, to begin with. Fans preferred the earlier shows' focus on humanity, and particularly how vampires could turn it off.
While fans enjoyed seeing their favorite heroes go bad, it was just as interesting to see how they came back from the dark side, as those scenes frequently got to the heart of what mattered to each character. Between The Vampire Diaries and Legacies, seven different characters turned their humanity back on, but some scenes took advantage of the opportunity for character development while others skipped right past it.
Jade
Legacies (Season 2, Episode 13)
After she lost control of her hunger, Jade killed her friend Inez and immediately turned her humanity off. It stayed off when she was sent to a prison world, making her delight in cruelty. Then, Josie forced her to relive emotional memories and her humanity was magically back on.
This plot twist was not well-liked, because it contradicted the original lore from The Vampire Diaries. While there was some precedent since Sybil brought Damon's humanity back, Jade had no emotional arc to deal with and Josie never explained how she did it, making it a disappointing humanity arc altogether.
Enzo
The Vampire Diaries (Season 5, Episode 19)
After learning Damon had killed the love of his life, Enzo flipped his switch and tricked Stefan into killing him to divide the two brothers. As a ghost, he remained vindictive and tried to torment Elena and the Salvatore Brothers. Viewers were then left to guess when and why Enzo turned his humanity back on.
He remained violent and vengeful in season six, but also seemed to genuinely care about Damon and Caroline. This feels like a case of weak writing more than an explicit choice to have Enzo's humanity come back over time, as it was hard to tell the difference between Enzo with and without humanity until later seasons.
Elena
The Vampire Diaries (Season 4, Episode 21)
Elena couldn't cope with Jeremy's death, so Damon used their sire bond to make her turn off her humanity. Getting it back on was not nearly as easy. They tried physical and emotional torture, but she finally responded when Damon snapped Matt's neck.
Elena began to feel, but quickly channeled all of her grief and guilt into trying to kill Katherine, which successfully stalled the full return of emotions until she finally went to Jeremy's grave. Loss is central to Elena's character, so it makes sense that losing her first love would wake her up, but some of her actions without her humanity involved trying to kill her friends, so it seems like an inconsistent trigger.
Stefan
The Vampire Diaries (Season 3, Episode 15)
Klaus compelled Stefan to turn his humanity off, but he didn't seem capable of turning it back on even when Klaus removed the compulsion. What finally did the trick, over the course of a few episodes, was Elena. Between his actions putting her in danger and her growing feelings for Damon, he started acting like his emotions were back on, though he wouldn't admit it.
It's debated what precise moment the switch flipped, but it is undoubtedly back by the finale when he was left sobbing over Elena's corpse. This was one of the most complicated times a humanity switch was turned back on because it's hard to say what actually brought him back. He had multiple minor crises that brought forth glimpses of humanity until it was all back for good.
Stefan
The Vampire Diaries (Season 6, Episode 18)
Stefan repeatedly tried to stop no-humanity Caroline from doing something she'd regret, which prompted her to make him turn his own humanity off. Thankfully, Stefan turned his humanity back on only two episodes later, when he reunited with his mother.
One of the more interesting parts of this scene was that Lily was actively lying to Stefan, as she fully intended to abandon him for her new family. The words she used were tailor-picked by Damon to bring back Stefan's pain and give him hope. Despite the deception, it was one of the easiest returns of humanity portrayed in the franchise.
Stefan
The Vampire Diaries (Season 8, Episode 11)
Stefan turned his humanity off in the final season to save Caroline's twins from Cade, but his Ripper side was more determined than ever to prove it had control. He killed Enzo in front of Bonnie, and his lack of remorse seemed to confirm Stefan was too far gone to come back. So Bonnie used the Cure on him instead, bringing his emotions back as he became human.
Stefan had no choice in his return to humanity this time, but he did have to face consequences for it. He was arrested, and while Caroline compelled him out of trouble, the guilt was crushing. The Vampire Diaries has asked before if a vampire should be blamed for their actions without their humanity, and Stefan certainly seemed to believe the answer, in this case, was yes.
Damon
The Vampire Diaries (Season 8, Episode 10)
Though Damon had his humanity off for large portions of his immortal life, audiences only saw it return once. Sybil forced him to turn off his humanity to do her bidding, and while he clung to a shred of humanity through his love of Elena, he killed many innocents, including Tyler. When he fought back against Sybil, she forced his humanity back on to torture him with his own guilt.
While Damon wasn't personally responsible for turning his humanity off or on, he did fight to keep his love for Elena and pushed himself into a mental Hell, so the emotional journey worked anyway. He and his friends were forced to confront the good and bad he did as a vampire, and the return of his humanity brought him one step closer to becoming truly human.
Hope
Legacies (Season 4, Episode 15)
Hope turned her humanity off when she was forced to kill Landon, which made sense given that she was young, plagued by loss, and overly attached to Landon on the whole. She went down a dark path but started to get her humanity back through a combination of Lizzie's companionship, her family confronting her with her father's ashes, and her own epic fight for control.
Hope took several episodes to regain her humanity, but her humanity took on its own form as a mental doppelganger. While it actually worked well to have Hope's morality be portrayed as a literal battle, the show's cancelation meant that fans hardly got to experience Hope after her humanity came back, limiting how effective the arc could actually be.
Enzo
The Vampire Diaries (Season 8, Episode 5)
Enzo was forced to turn off his humanity by Sybil, but the way he turned it back on was critical to why some parts of season eight worked so well. Though it had a rushed introduction, Enzo was given an epic love with Bonnie that rivaled Damon and Elena's. Bonnie set their cabin on fire—trapping herself inside— to force him to turn his humanity on or watch her die.
This strategy proved incredibly successful, as Enzo's love for Bonnie surpassed any reason for keeping his humanity off. He is the only vampire shown to immediately turn his humanity on at the sight of his partner in mortal danger, which proves that Bonnie and Enzo were the best couple on The Vampire Diaries.
Caroline
The Vampire Diaries (Season 6, Episode 19)
Caroline planned to turn her humanity off for a year, but Stefan made her turn it back on after a far shorter time period. He head-dived her, creating the illusion of her mother rejecting her and then showing a memory between himself and Liz about finding the right words to say to Caroline, alluding to a letter that Caroline had previously forced Stefan to burn.
Caroline's love for her mother made for one of the most consistent representations of humanity in the franchise. She turned it off out of grief and turned it on because she realized she'd never know her mother's last message for her. The idea of never getting another conversation with her mother was painful but realistic and made for the most powerful return of humanity in the series.
Source:gamerant.com