Enjoy! :D

After she left the Salvatore Boarding House, Caroline ran to Bonnie's house and began pounding on the door.
"Bonnie! Bonnie! Bonnie! Bonnie!" Bonnie opened the door.
"Caroline! Caroline! Caroline! Caroline! What is it?"
"I think I've finally pieced together what happened this past month. I'll explain but after I do, we need to put the final piece in our plan in motion."

Damon drove up to the Boarding House and got out of the car and began walking towards the front door. He looked behind him to make sure that Elena was following him.
"Why are we here",she asked.
"Don't worry, you'll live. Maybe",he muttered under his breath.

After explaining everything to Bonnie, they finally got started on the last phase of plan "bring Stefan and Elena back together" and they even began plotting a bit of plan "drive Damon and Katherine out of town". Bonnie was currently preparing another special "brew" (as Bonnie put it) to help bring back Stefan and Elena's memories of each other again. After Caroline had explained that the powder from the night before was only temporary, Bonnie began getting a permanent one ready.
"Okay. It's almost done. I just need you to do one thing",Bonnie explained. She reached behind her and brought out a sharp dagger.
"What the hell?"
"I need you to add some of your vampire blood into the brew."
"Why?"
"Does it really matter?"
"Um, YEAH!"
"Do you want Stefan and Elena back together or not?"
"Fine. Give me the stupid dagger." Caroline took the dagger from Bonnie's hand and cut her palm open so that the blood spilled out in scarlet drips. Bonnie began chanting.
"It's done",she whispered after about 5 minutes of creepy chanting.
"Now what?"
"Now, you go to the Salvatore House and try to get both Stefan and Elena to drink these." She handed Caroline two small vials.
"And if I can't convince them to drink it?"
"Force feed it down their throats, duh."
"Okay. Here goes nothing." Caroline grabbed the vials and ran out the door.

Caroline had to find an entrance into the Boarding House that Katherine couldn't see. Meaning: She couldn't just waltz through the front door. So, she looked at every window, praying that one, just one would be unlocked. Almost all hope was lost until she finally found one unlocked. It was Stefan's balcony door. I might as well kill two birds with one stone. She carefully jumped up onto the balcony and pushed open the doors as quietly as possible. The door only made a small creak as she closed it once she was inside. Looking around, she found a mug filled with coffee. Just as she was about to pour the vial's contents into it, Stefan came into the room.
"Caroline?"
"Stefan! Hey."
"What on earth are you doing here?"
"I-just." She was really left with no choice now that she had been caught. She advanced towards him, opened the vial, and shoved the liquid into his mouth.

Once she was done with Stefan, Caroline made her way downstairs. She had to distract Katherine somehow to get her away from Elena. Looking around, Caroline spotted a vase on the coffee table. She picked it up and slammed it onto the ground as hard as she could. The vase made a huge shattering sound and Caroline ran and hid behind the basement door. Soon enough, she heard footsteps coming up the stairs and watched as Katherine stepped into the living room.
"Nothing here",Katherine thought out loud. "I'll go check the kitchen."
As soon as Katherine had entered the kitchen, Caroline made a mad dash downstairs. When she got there, she looked into the cell where Katherine had left the door open, and saw her best friend strapped to a chair.
"Elena! Oh my God",Caroline yelled when she ran to untie Elena.
"Caroline?"
"Yeah. It's me. There. Now come on! We need to go now!"
"Okay and thanks Care."
"My pleasure. Now let's go!" Caroline helped Elena steady herself and made the other girl hang on as she ran with most of her vampire speed up the stairs.

When they got to the living room, Caroline saw what she last thing she had wanted to see. Katherine.
"Did you really think I wouldn't see you hiding behind a door? And did you actually consider that I wouldn't hear you talking to Elena? Because let's face it, yelling your best friend's name isn't very subtle. But, I really don't care about you Caroline. So I'll let you leave or I'll kill Elena. Got it?"
"Fine. I'll go. But first." Caroline pulled out the second vial from her pocket and shoved into Elena's mouth. Elena gasped and began coughing.
"What did you give her?!"
"Don't worry about it. Bye bye Katherine",Caroline said before she ran off.

When Elena finally stopped coughing, she felt a tidal wave of images flooding her mind. Stefan. Stefan Salvatore. All the images were memories, with the exception of three of them. The three final images were of Katherine compelling her to forget Stefan.
"WHY DID YOU COMPEL ME",Elena shouted.
"Because, I wanted Stefan. Besides, you looked so happy with Damon."
"With Damon?! I spent a whole month alone with Damon?! Damon Salvatore of all people!"
"Get over it. Now, get back downstairs and we'll continue what we were doing. And once we're done, I'll patch up your mind and you'll be head over heels for Damon again."
"Head over heels for Damon?! Over my dead body!"
"That can be arranged, and you didn't let me finish. After your memory is patched up, you'll go back to Fell's Church, forget completely about Stefan, and live the rest of your days with Damon and the rest of Stefan's days will be spent with me."
Elena moved towards the fireplace. "I'd rather die than live 'the rest of my days' with Damon." Elena picked up the poker that lay next to the fireplace.
"Don't you dare, Elena."
"I do dare, Katherine. I'm done being your leverage to Klaus and I am definitely done being your toy." Elena brought the poker closer to her body. "Tell Stefan I love him."
She never said anything else, for that was the moment that she drove in the poker.

Elena! So Elena's dead now and Katherine just lost her leverage over Klaus. Any theories about what's still to come? Stay tuned...