She ran from him for weeks, but eventually, Damon helped Silas lure Katherine to the house and fed him her blood, which turned him back into a witch. Though Katherine should have died after Silas completely drained her of blood, Katherine's survivor instincts won out, and she managed to live through the attack.
Elena force-fed Katherine the Cure in Graduation. The Cure was in Katherine's blood. Then, Silas fed from her and it passed on into him and also turned him into a warlock again. Then, Amara fed from Silas in order to become human, so the cure is now inside of her..
It is later revealed that after having the cure drained from her, that her 500 years is starting to catch up to her, and only had a few months left to live. This wouldn't have happened if the cure wasn't drained from her blood. She would have aged normally had it had not been removed from her blood.
After Rose discovered that Katherine had stolen the moonstone from Klaus, she told Katherine she was going to turn her over to Klaus rather than risk her and Trevor's lives. She fed Katherine her blood to heal her wounds. Then when Rose left the room, Katherine hanged herself and became a vampire.
Elena still had most of her natural human life span ahead of her, and that's the reason, even without the cure in her system, she lived on.
Dead supernatural beings pass through bonnie. Katherine was a human when she died... Bonnie wouldn't expect for katherine to pass through her. 71.125.
The sleeping spell she's locked in stops her aging. But that is just temporary immortality, which means that the only thing stopping her from aging 60-odd years will be the cure in her blood.
There in England, in 1492, Katherine met Klaus, who she was taken with until she found out he wanted to drain her blood to lift a vampire curse. She ran, with Trevor's help.
For centuries, Klaus continued looking for ways to break the Hybrid Curse, for which he needed a Petrova doppelganger. The ritual that could undo the curse also needed a witch to channel the power of a full moon into the moonstone. Then Klaus would need to sacrifice a werewolf and a vampire.
Julie Plec confirmed that Klaus is the origin of the bloodline Stefan, Damon, Caroline and Elena are from. It is possible to unlink a vampire from their bloodline using magic. This was successfully performed on Klaus by Davina. For reasons unknown, Klaus never sired new vampires after his sireline was severed.
Throughout The Vampire Diaries
In the season four finale of The Vampire Diaries, Graduation, Katherine slept with Niklaus Mikaelson and conceived her daughter, Adyelya.
The Ripper Virus/Ripper Compound was most recently injected into Elena Gilbert after being enhanced with werewolf toxin, making her more rabid and deadly than even Damon.
Silas shows his true form, which is exactly the same as Stefan's.
She ran from him for weeks, but eventually, Damon helped Silas lure Katherine to the house and fed him her blood, which turned him back into a witch. Though Katherine should have died after Silas completely drained her of blood, Katherine's survivor instincts won out, and she managed to live through the attack.
When Damon attacks Silas later, Bonnie, in a moment of confidence, uses expression to petrify Silas. Damon and Alaric then put his body in the trunk of Damon's car. At the end of Graduation, Silas reveals to Stefan that when Bonnie died and closed the Veil, the spell she cast on him also ended.
Silas transferred the Cure to himself by drinking all of Katherine's blood, becoming mortal once again. Shockingly, this didn't kill Katherine. However, Silas' actions revealed a dangerous side effect of the Vampire Diaries Cure: once it was removed from Katherine's body, she began to die of old age.
The Doppelgangers are Born
The Petrova doppelgangers are a bloodline of women who look exactly like the original Petrova doppelganger, Tatia. There have been five known Petrova doppelgangers throughout The Vampire Diaries: Tatia, Katerina, Elena, Stefan, and Tom Avery.
Amara is the oldest known ancestor of the Petrova family or bloodline, being born some time during 1st Century B.C.E. (100 B.C.) in Greece. Amara was originally human but became the world's first immortal woman after she consumed the immortality elixir. Amara is assumed to be of Greek origin or descent.
Tatia. The first Petrova doppelgänger, Tatia, lived during the late 10th/early 11th century. Amara had no children, so Tatia was linked to Amara though a child of one of Amara's siblings.
After a werewolf dies with Klaus' blood in their system, their transformation will be successful only if the wolf completes their transition by drinking the blood of a human Petrova doppelgänger. After Elena transitioned into a vampire, her blood became useless to Klaus and he could no longer create more hybrids.
The family relationship between Klaus Mikaelson, Katherine Pierce and their daughter, Adyelya. Klaus and Katherine conceived her in Mystic Falls after Klaus encountered a newly-turned human Katherine in the Mystic Falls Grill. After a night of drinking, the two of them had a one-night stand.
Literally the explanation is that Klaus was born a werewolf, so he can procreate. Every hybrid on the planet was born a werewolf. The CANON ANSWER is that he triggered the curse thus he can procreate. Tyler transitioned to a vampire thus he could not procreate.
Last night, Vampire Diaries fans watched as Elena Gilbert was put into a magical coma when Kai linked her life to Bonnie's. So as long as Bonnie is alive, Elena can't be, which means that Elena went into a 60-plus year sleep in order to allow her best friend to attempt to find happiness.
Elena's Coffin was the coffin where Elena Gilbert slept due to the sleeping spell that linked her life to Bonnie Bennett's life. It was used to protect her until she woke up when Bonnie died.
As the youngest writers on staff, Badillo and Levich related to Elena's point of view and felt that the character losing her virginity at 17 wasn't a big deal.