Disclaimer: I don't own Code Geass
This is just something I made up so enjoy
Exactly one month has passed since Lelouch the Demon Emperor died. One long harsh month and Kallen knows Lelouch's plan was to bring peace which he did.
"Kallen a letter has come for you" Kallen's mother calls. Kallen grabs the letter and notices that there is no return address just an invitation to a funeral, Lelouch's funeral to be exact. Kallen looks everywhere on that letter to find out who wrote it but she quickly learns as she begins to smell pizza.
"C.C" Kallen mutters. The letter states that in one week he will be buried privately and a private jet will take her to the site
A week later Kallen finds the plane and heads to the funeral. There are very few people here at the funeral: Nunnally, Zero who is actually Suzaku, Jeremiah, Sayoko, and herself. She looks around "where is C.C?"
After all the crying tears and hope that Lelouch's world without war stays Kallen meets C.C at the very back hidden by a black cloak "C.C here you are, why aren't you with the others?"
C.C just looks at her "now that he is gone all I have is more accumulated memories and he is the only one who made me feel human"
"C.C give me geass, I want to complete Lelouch's last order"
"Last order?" C.C asks
"Yes to keep this perfect world I will become its guardian"
"So that is your purpose to live now, very well but to do that you will need to fulfill my wish when the time comes"
"I accept" With that Kallen gains the power of geass but no one ever knew what it was or what it was capable of.
One year later C.C returns to her and looks into Kallen's eyes and sees the symbol of geass in both "Kallen your geass has become very powerful and I see you can't control it" all Kallen can do is nod her head "now it is time for you to fulfill your end of the bargain" C.C hands Kallen a gun "shoot me and become immortal, then you can forever protect his world" Kallen hands begin to shake. She couldn't pull the trigger not on C.C. but C.C doesn't give her much of a choice "Kallen if you don't shoot me then I will be forced to take away your geass by ending your life" C.C steps closer to her about to strangle Kallen like she was when the priest passed the code onto her. Kallen begins to get choked and pulls the trigger making C.C fall to the ground permanently dead.
She kneels down beside C.C "I know you never meant to do real harm to me you just wanted to be with Lelouch, so I will protect his world for everyone's sake" Kallen runs off into her knightmare with a symbol of geass on her head.
She fly's around the world stopping wars before they escalate and ensuring Lelouch's world peace
Sorry for not telling you what Kallen's geass is I coudn't really think of one anyway i hope you enjoyed it