What is a good name for a person named Si?

I am a "thinker"---that is, a person who thinks about random things every day when he has nothing to do. What a coincidence, I happened to think of a name for the protagonist of my new novel some time ago--- Si Zi, if you don't mind it, just make do with it. If you adopt this name, then I will replace "Si Zi" and choose someone else.