Who is Christian writing about on his typewriter in Moulin Rouge?

In the movie *Moulin Rouge*, Christian, played by Ewan McGregor, is writing about Satine, played by Nicole Kidman.

He's writing a play called "Spectacular, Spectacular" for her, which is a love story inspired by their relationship. The play is a way for Christian to express his love for Satine and to try to capture the magic and passion they share.