It was a nebulous night at an abandoned house in Mystic Falls, as a human Katherine walked over to the door to answer it, having heard the doorbell ringing in her sleep. She was worn out due to escaping Kai in a prison world and just wanted some sleep. Was that too much to ask for?
When she opened the door, she immediately recognized Hope. She had known that Klaus had a daughter and knew that she would be three years old right now. She also knew that Hope was half hybrid and half witch and needed to be protected.
"May I help you?" she asked the stranger holding Hope. Even though he was a stranger to her, she had a guess what he was. He was a werewolf, considering the demeanor he had.
"Are you Katherine Pierce?" he asked her calmly.
"Yes," she replied.
"The Mikaelsons and Hayley sent me to give you Hope to take care of. They are unable to right now. They want you to take care of her until they can come for her, once Hayley finds the permanent cure for Elijah, Kol, and Freya now that Marcel has bitten them and Freya has been poisoned and Rebekah has been cursed. They trust that you won't let any harm come to the child," he said, answering her question.
"And what of Klaus?" she asked.
"Marcel has him in a wall of the Garden and Klaus is linked to them while they are daggered."
"Thank you. You can assure Hayley that no harm will come to her as long as I live."
He gave her Hope and a bag of Hope's stuff and her car seat, before walking away.
She closed the door and walked over to the living room, before setting the stuff down. She then looked at Hope and gave a sigh. How could such an innocent child be in danger already? What the hell happened in New Orleans that caused Marcel to turn into a monster and nearly kill the only family he had ever known in his vampire life? She hadn't know him as ruthless when she had been a vampire. He was the sweetest and purest vampire she had ever met before Caroline and Elena had come along. Marcel had always had a good heart. IF she didn't have Hope to keep safe, she'd be going to New Orleans right now to settle things. She was beyond angry and disappointed. Had he not been thinking clearly? An attack on Elijah was an attack on her. She didn't know Freya or care about Kol, and Rebekah had always despised her, and she and Klaus had never seen eye to eye, but when it came down to Elijah, that was a completely different game altogether. If you hurt Elijah, you were also after her.
"Don't worry, Hope. I'll get you back to your family as soon as I can. Marcel won't get away with this. For now though, you and I will have to take care of each other," she promised out loud to both Hope and herself.
Six months later, after a while of being settled in a small town some miles away from New Orleans, working for money for the house she was living at with Hope, with the story of being a single mother, she finally found a way to cure them. Hayley was traveling to where the cure was at, while Katherine was driving her SUV towards where they said that they would meet.
Hours later, after delivering Hope to Hayley and while Hayley cured them, Katherine drove to New Orleans. Human or not, she wasn't afraid of vampires nor werewolves nor any witches who would stand against her. She had Traveler magic and wasn't afraid to use it.
A few hours later, aware that vampires were watching from the shadows but didn't care at this point, she entered the compound. This was between her and Marcel.
"Marcel!" she yelled, as she briskly walked in, technically storming in.
Marcel came to stand in the middle of the compound, which she approached and gave him a slap across the face.
"How could you!? Are you that inconsiderate!?" she yelled at him.
He was confused by her outburst for the moment.
"I'm not sure what you mean, Katherine, but I'm sure whatever it is, I can fix it." He didn't want Katherine of all people angry at him. He knew better than to make an enemy out of her.
"Oh, Hayley and I have already figured out how," she said angrily. "That doesn't get you off the hook, though. You bit Elijah knowing that there was no cure! Not only that, but you took Klaus away from Hope! I was stuck taking care of her because you weren't thinking clearly! Now Hayley and I are stuck cleaning up your mess," she clarified. Then she added, "I'm taking Klaus out of here and to his family. If you want to stop me, you're going to have to kill me. After that, you and I are going to have a showdown. You almost killed the wrong person and family. I may be between enemy and ally and friend to them, depending on the situation, but I would never put their lives at risk. Klaus' sire line may be broken, but I've got people in Mystic Falls I care about who I don't even know which Original bloodline they fall under. IF they were to die because you were careless, I would kill you on the spot and you know it," she said. If the Salvatores and Caroline weren't part of Klaus' bloodline and Klaus' siblings died, she couldn't imagine a world without them.
"Look. I'm sorry, okay? You're right. I wasn't thinking. How else was I going to get them to leave though? They had to fear me so I can be king again without their interference. Everything they touch always dies sooner or later."
"And you put Elijah's life on the line in the process, knowing that I'd find out sooner or later, and seek my wrath upon you."
"All I can do is apologize."
"Don't. An apology is something Elijah would want to hear. Not me. You crossed the line. We're not friends anymore."
She walked into the Garden and used magic to take the wall down all at once. Then she got him on his back once she had him out of the wall. Then she used magic to get Papa Tunde's knife out of him.
After undoing the sleep spell, all the siblings woke up and were cured.
"What have you done, Katerina?" Klaus asked.
"I just saved you all and had a talking down with Marcel. You can go see your siblings. I'll meet Elijah later. Marcel and I have a score to settle after what he did to Elijah; to all of you."
"Then I guess we'll see you soon, luv."
He gave a smile.
Once he'd gone, she stood face to face with Marcel, magically turning him back into a normal vampire.
After Marcel was a normal vampire again, all he could do was look at her with anger and shock. He hadn't know that she had magic of her own, and he wasn't thrilled at her doing what she had to him.
"What have you done?" he growled at her, but made no move to harm her.
"Don't you get it, Marcel?" she said. "I'm not going to kill you. This is your punishment until someone kills you."
Before he could say anything else to her, she left to go make sure Elijah would live to see another day.
Later that night, Marcel was killed by Elijah and they got their home back, but after Kat and Elijah got back together and she told him that Klaus knew about her dying, she and Elijah left town. So, Kat and Elijah got their happy ending, Kol left town too, and Rebekah and Freya stayed at Klaus' side.