What is the comparative and superlative of demure?

The word "demure" is already in the superlative form. There's no comparative or superlative form for "demure" because it describes a quality that isn't measurable in degrees.

You could use words like:

* More reserved (comparative)

* Most reserved (superlative)

* More modest (comparative)

* Most modest (superlative)

* More unassuming (comparative)

* Most unassuming (superlative)

These are alternative ways to express the idea of being more or most demure.