Disclaimer I don't own Code geass or its character. If I did this is how I would have ended it.
This is how I would rewrite Episode 25.
Kallen and all those who had rebelled against Lelouch were sitting in cells. Kallen didn't know where the rest were. She had been blindfolded and brought to her cell. She figured it had been two months. She didn't know what to think of it all. Was this it? Wasn't Zero for Nunnally's sake? Were all those feelings and moments between them just in her mind?
As she slept she heard someone coming near her cell. She had heard the same noise almost every night. It was footsteps and then sobbing. She though she heard whispering on a few occasions. As far as cells go hers wasn't bad. Everyday some geassed slave brought her food. Finally this night Kallen decided to try something. As she lied there she waited for the noise. It came. Kallen walked over to it.
"Lelouch, is that you?"
Kallen heard a gasp.
"Why do come every night and not say anything."
"Kallen tomorrow is the day. It ends tomorrow."
Kallen gasped. "I die tomorrow."
"No Kallen, I die tomorrow and the world can begin with a clean slate."
"For Nunnally. I couldn't let her do it. She wanted Damocles to become a symbol of hate. But in a hundred years who will remember Damocles and FLEIA. They will simply be casual weapons of war. No but Lelouch the demon emperor will be remembered forever and hated."
"Lelouch it's my fault. I abandoned you again. First with Suzaku and again when the Black Knights turned on you. I should be your Knight. Your Knight of Zero."
Kallen sighs and begins to walk away.
"You are my Q1 my black queen. You should be ruling beside me."
Lelouch entered the cell. He was alone.
Kallen thought was this what he was waiting for. He was wearing a simple shirt and pants. She could kill him or at least knock him out and get away. No this is a test.
Lelouch simply looked at her.
"Kallen, what should I do?"
"Lelouch, why does anyone have to die? Zero was for Nunnally's sake. Zero was for Japan. For the world"
"Yes I have accomplished all my goals. I have redeemed my mother's and sister's death. But I need to create a world for Nunnally."
Lelouch sat down. Kallen sat down beside him.
"Lelouch, how can you create a world you are not a part of. Lelouch, simply be the best emperor you can be."
Kallen lied down on her bed. Lelouch kneeled down beside her.
"Kallen, if you are be my side. I think I can do it."
Kallen thought, she had rejected Britannia al her life, now here was the chance to be its empress.
Lelouch began to walk away. Kallen looked at him. A chance to save her friends and the man she loved. Naoto what do I do.
"Lelouch wait. What must I do?"
CC walked into the room. Of course the immortal witch was near. She walked up to Kallen.
"To save those you hold dear. You must agree and then fulfill the contract."
Lelouch raises his hand. On it is the same symbol that CC has on her forehead.
"What is that?" Kallen asks.
Lelouch looks at his hand. "It is the symbol of the immortal."
CC looks perturbed. "Do we have a deal?"
"What are the terms of the contract?"
"Well eventually you will have to kill me… Or him. But I would prefer myself since I would like to extinguish the accumulation of this life. But if you reach the moment and want to get rid of him, I will understand."
Kallen shook her head what time to be joking.
"The reward for the contract."
"Apart from saving those you love. I guess you get to spend eternity with him."
CC points her thumb at Lelouch.
Kallen thinks kill the pizza girl witch.
"Well I tried him but he cheated. Not only did he steal his father's code and throne but the imbecile got to keep his power. Not fair. So now he won't keep his promise. What a liar."
Kallen looked at Lelouch who is standing still.
"I'll do it."
CC nears Kallen. Suddenly Kallen sees what appears to be a maze. Suddenly she feels different. Kallen's left eyes glows red. Kallen sighs.
"What happens now?"
Suddenly Nunnally is being pushed into the room by Suzaku.
"If you're going to be empress you have to marry brother."
"I guess that was part of the contract. What about the others?"
Lelouch walks towards Kallen.
"Let's surprise them tomorrow."
It was a simple ceremony. The only attendees were Suzaku, Nunnally, CC, Milly (which of course was a surprise for everyone), Kallen's mom, and, of course, Lelouch and Kallen. Kallen was afraid that CC would conduct the ceremony. Kallen was glad her mom was there. Milly made a quip about the wedding night. Nunnally giggled. Everybody else blushed. Of course there would be no wedding night until everyone was free. However Lelouch still made Kallen sleep in the same bed. Kallen was lying in their bed. It was going to take a while to get used to that. She promised her mom she would finish school. Was that even necessary for her? Kallen thought for a moment about something. She looked at Lelouch and suddenly she hit him.
Lelouch thought great we haven't been married a day and she's already hitting me.
"What is it?"
"That mark means you're immortal."
"More or less."
"You have the same powers as CC."
"Pretty much. Except she had more time to learn things."
"That means no matter what would happen tomorrow you would have survived."
"Couldn't I have made a contract with you and still killed the pizza girl?"
"I think so but it's better not to take chances."
"Lelouch, what do you have planned tomorrow."
"It's a surprise."
"I don't think you're allowed to hide thing from your wife."
Lelouch doesn't answer. Kallen sighed. She would have to trust him. If they had trusted him all along, things would have turned out better. She leans into him. He puts his arms around her.
The parade route was set. The prisoners were set. Milly and Rivalz look on in disbelief. The Black Knight leaders were lined up in two rows. Schniezel and Nunnally had special places of dishonor. In front of them were Britannian soldiers led by Jeremiah. Behind them was the emperor's throne, it was hidden from the view of the people. Tohdoh looked around. He had fought an honorable fight. He noticed Kouzuki was not there. He looked at Ohgi who just looked down.
The announcer proclaimed. "The prisoner Kallen Kouzuki/Stadtfeld was killed last night trying to escape."
Ohgi began to cry. Tamaki lets out yell. Suddenly the parade stopped. Out of the emperor's carriage came a figure. It was Suzaku Kururugi. The Black Knights gasped. He was supposed to be dead. Everything they had fought was lost. In their eyes evil had won. Kallen was dead. The demon emperor and his knight lived. Behind Suzaku came another figure wearing a familiar costume and mask. It was Zero. How dare he mock them with this at this time?
Zero reached form his mask. But instead of the raven haired boy, it was the red haired Guren pilot. She was alive. Suddenly behind her came Lelouch. He was dressed as the emperor. Kallen went back into the carriage. Lelouch pauses for a moment as he looks around. Suddenly he began to talk.
"I would like to present to everyone my Q1, my black queen, my empress Kallen vi Britannia."
Kallen walked out dressed every bit the empress. She bowed before Lelouch. Suzaku walked down the steps towards Nunnally.
Lelouch continued, "As we have just been recently married, I have decided to grant my wife a wish. Anything she wants today she can have."
Ohgi lifts his head. Tamaki can't believe what just happened.
"I, Kallen vi Britannia, command the prisoners to be set free and their charges dropped."
"Anything else my dear?" Lelouch asks while sitting on the now visible thrones. He is playing with the Zero mask.
"Yes from this day forth Japan will be free."
At first nothing is being done.
Lelouch stands up. He goes forward.
"The word of my wife is as my very own. I, Lelouch vi Britannia command it."
With that the prisoners are set free. They begin to hug each other. Suzaku frees Nunnally and carries her to Lelouch. They hug. Nunnally goes to Kallen. Cornelia and her group are still in their room unsure what to do. Suddenly a phone in the room rings. The name Ohgi appears on the screen. Villetta is unable to contain herself. She answers it.
Villetta begins to cry.
"I knew you would answer. Are you are come down?"
Villetta rushes out. Outside the former prisoners are celebrating. Lelouch notices Kallen is anxious to see her friends. But none dare to come up. Lelouch signals her to go down.
Kallen runs down. As she approaches them, they stop celebrating. Tamaki raises his hands. He gets on one knee.
Everybody follows Tamaki's example.
"All hail Kallen vi Britannia."
Kallen blushes. She jumps at Ohgi. She signals behind them where Villetta has appeared.
Kallen walks over to Chiba. She is by Tohdoh.
"Your highness," Chiba says as she giggles
Tohdoh simply bows.
Kallen looks at them "I have a royal request for the two of you."
Tohdoh looks at Kallen. "Is it of military importance?"
Kallen shakes her head. She points to the side. Just then Tamaki and Ohgi push Chiba and Tohdoh together for a kiss. Chiba is the first to break it off. She is blushing
"Forgive them Colonel."
Tohdoh looks around.
"No forgive me," Tohdoh says as he grabs Chiba and kisses her again.
Meanwhile up in the emperor's carriage Nunnally sit in Kallen's throne. Lelouch looks at Nunnally.
"You look good on the throne."
Nunnally laughs. "No brother. You are emperor. I don't know if I could have done what you did."
"I'm sorry I lied. I'm sorry about Euphie and everything."
Lelouch begins to cry. Cornelia approaches the throne. Suzaku is there.
"Its fine Suzaku," Lelouch tells him. "It doesn't matter now." Lelouch points to his hand.
Cornelia looks at Lelouch and Nunnally. Kallen comes up to the throne. Cornelia looks at Kallen.
"Take care of my brother. Maybe you can fix him? If you need anything I can help? I owe Euphie that at least."
Guilford comes for his princess. Jeremiah comes to take the royal family away.
The celebration will continue without them. They leave to Ashford Milly, Rivalz and Nina are there waiting with fireworks.
Two years later
CC is working in her garden. She feels someone come up behind her.
"So your highness it is finished."
Kallen pulls out her pocketbook with the knife.
Kallen finishes CC. Suddenly upon Kallen's forehead appears the symbol that had been on CC's forehead.
"Goodbye pizza girl.
Author's note: There's my story. I think it is plausible if Lelouch and Kallen had trusted each other. Also I took note of Tamaki's dislike for Britannians and made him the first to bow to Kallen. Of course since Kallen has her love she tries to make everybody else happy. I made Kallen kill CC with her little pocketbook knife thing because it was about time somebody died with that thing. I plan on using a little different version of the final scene in a different fanfic. Also I have another scene after that where Kallen goes home to her family. Also I didn't specify Kallen's geass here but if anyone has a cool geass power I could add a scene or two where she uses it. Of course I have other fanfics where she could use it. It would probably have to be useful in battle and not drive her crazy. Something like Bismarck Waldstein's geass would work
I was going to write this note originally but forgot. Has anyone written a fanfic where Sayoko is dressed as Lelouch at the end. You know Sayoko decides to take one for the team. I think it's a funny concept. Sayoko dies in Lelouch's place, and Lelouch and CC off eating pizza somewhere. Then you know he can come back. It's pretty simple just wanted to throw that out there.