It takes her 15 years, and it only takes that long because between her own kids and the school, she's a little busy. Truthfully, she started the minute it became clear he planned to sacrifice himself. It wasn't just that she couldn't watch him die… she was hoping to stop it. But sometimes the timing is off, so she adjusts and searches for a way to bring him back instead.
She doesn't tell Hope – she doesn't want her to become too optimistic, just in case. But Caroline is, well, Caroline, and she doesn't half ass anything. She talks to dozens of witches, conducts thousands of hours of research. If she's learned anything in her immortal life, it's that the impossible is always possible. And it's that determination that helps her find the witch who tells her it can be done.
Caroline was expecting to find her deep in some jungle or on some nondescript island. But life never ceases to throw Caroline for a loop, and she finds the witch in Oxford. She's powerful, but not incredibly well known so she's been able to hide herself well. Her skill comes from her profession – she's a physics professor and researcher, and uses it to add layers to the magic. After all, even magic has to obey some laws.
The first person she calls is Rebekah. Thanks to Hope, they've kept in touch. After all, someone needed to come to parent teacher conferences, and it turns out they can get along pretty well when they're on the same side.
Rebekah picks up after the first ring. "This has better be good, because I'm about to indulge in my favorite Italian and I hate interruptions."
"I found it. I can bring him back." She hears Rebekah take a sharp breath, and her voice has the slightest shake to it when she responds.
"Are you sure?"
"Yes." Caroline is confident, voice assured. "How soon can you be in Mystic Falls?"
"I'm leaving now," Rebekah replies, and Caroline can hear her moving quickly. "Where are you?"
"England."
"We'll pick you up on the way. See you soon."
It takes a couple of hours, and Rebekah, Marcel, and Caroline are on their way back across the pond. Even with advancements in technology, the flight will still take a few hours, so Rebekah asks Caroline to explain how this is possible and how to do it.
Caroline thoughtfully sips her red wine. "I found the witch at Oxford, teaching physics. She's also a part time researcher." Rebekah raises her eyebrows. "Yeah, I was surprised, too. Anyway, everyone I had talked to said she was capable of unique pieces of magic, things that aren't normally done. She's got a skill to craft the spells. Basically, she said it's possible to bring him back by weaving the magic with the elements of physics."
Marcel raised an eyebrow. "What in the world does that mean? I mean, if there's no Other Side, where can they bring him back from?"
Caroline replied, "That's what I asked. She said it comes back to one of the most basic laws of physics – energy is neither created nor destroyed. And the entire universe is made of energy. We as individuals are unique combinations of that energy, so by honing in on it, you can essentially rebuild the person you are reviving. We can capture their energy from the universe."
Marcel and Rebekah were silent, trying to make sense of what Caroline was saying. "If that's possible, how come we haven't heard of it before?" Rebekah asked. "Surely someone would have done it."
Caroline smiled. "As always with practically anything connected with Klaus, it takes unique circumstances." Rebekah smiled at that – Caroline wasn't exactly wrong. "You need a blood relative, which is where you come in, and a direct descendant. The direct descendant shares the most genetic material with the individual – exactly half. Really, half their energy is that of their parent. The blood relative helps fill in the gaps. How many vampires do you know of with direct descendants? That's why it hasn't been done often. Really, I think it's mostly theory, but it seems sound to me. After all, what is there to lose?"
"Indeed," Rebekah quietly mused.
The rest of the flight is silent, each lost in their own thoughts. No one wants to get too optimistic. During the drive from the airport to Mystic Falls, they hash out the details.
"So when is this all gonna go down?" Marcel asks.
"Full moon, as always." Caroline laughs.
"Ah yes, so original!" Marcel comments. "My apologies for thinking we were going for something unique." His smile is contagious, and soon Caroline and Rebekah are both laughing with him, but they soon quiet.
"Hope will be the one to do the spell. The witch wrote it out for her. I think we should do it at the old Mikaelson mansion. We don't know what he'll be like when he wakes up."
Rebekah glances at Caroline, who is laser focused on the road. "When? You're awfully confident."
Caroline gives her a rare moment of heartfelt honesty. "I have to be Rebekah. I refuse to believe that I'll never get him back. However long it takes."
Rebekah recognizes the words she's seen on some of Nik's drawings and paintings of Caroline, and she puts her hand on Caroline's shoulder, trying to convey that she understands. Caroline gives her a small smile.
Marcel is quiet when he speaks. "This will work. I can feel it."
They pull up to the mansion where Hope is waiting for them. Rebekah had called her during the drive, explaining that they needed to speak with her urgently. As they climb out of the car, Hope is surprised to see Caroline.
"Ms. Forbes, what're you doing here? I thought you were traveling looking for new students."
Caroline walks around the car and stands in front of Hope. She smiles. "Not quite. Once upon a time, your dad promised to be my last love. I found a way to make sure he keeps his promise." Caroline can see the confusion in Hope's eyes slowly morph into a shaky optimism.
"You mean?" Caroline nods. "You can really bring him back?"
"You can. You and Rebekah. I found a witch who wrote it all out, and Rebekah will be able to explain it to you. If you need anything, you can call me."
Hope looks puzzled. "Where are you going?" Rebekah and Marcel come to stand beside Hope.
"I'm going to go see my girls, and a few other people. Besides, you should be the first person he sees when he wakes up. He and I will talk eventually." Caroline turns to Rebekah. "You have my cell if you need anything."
Rebekah reaches out to her, and gives her a rare hug. "Thank you," she whispers. They separate, and Caroline gets in the car and drives away.
Hope turns to her aunt. "Why won't she stay?"
"She's right – your dad will want to see you first. But, Caroline's also nervous." They begin to walk up the steps into the house. "I don't think she ever told Nik how much she truly cared for him. And I don't think she ever truly grieved his loss." The came to the door, and Hope was silent.
"She was searching for a way to bring him back all this time?" Her aunt nodded and Hope looked thoughtful. "Well, what are we waiting for?"
It doesn't take long to perform the spell. Something about energy and the four winds, Rebekah hears. Hope is strong, and this was a big spell, but she does well. It took 18 hours for the energy to slowly stitch Klaus back together. It's another five before he begins to stir. Tears gather in Hope and Rebekah's eyes, and Marcel is holding Rebekah's hand so hard she thinks her bones are probably cracking.
Klaus's eyes slowly open. Hope lets out a breath she didn't know she was holding and grasps his hand even tighter, sobbing when the hand squeezes back. It worked. Somehow, it worked.
"Dad?" Her voice is watery and shaky and this isn't how she imagine she'd meet him again, but she doesn't care.
Her dad smiles. "Hello, sweetheart."