I was surprised to find out last month that there is a Code Geass Alternate Ending. It was on a Code Geass Club in MyAnimeList.net. For all those who who watched Code Geass, you should read it. It provides a new hope for Lelouch’s fan.
Anyway, if you want to know what happened just highlight the spoilers:
C.C. died for Lelouch. She said that when she thought about how she’ll spend eternity without him, she was saddened. So she gave the sigil to Lelouch. Oh, she also kissed him! Lelouch after crying a li’l bit, told Suzaku to continue killing him. He fell down to Nunally like in the anime. Then, Suzaku sealed him in the same container C.C. was sealed. Nunally tried to stop him saying, don’t leave me alone again… But Lelouch said that the Geass and him are threat to the peace of the world. Then, years years later, somebody opened the container who looked a lot like Nunally… his requiem ends and the rebellion begins.
Read it here. The drawing are not as good as the anime but it’s okay. You should check it out.