You can't "grow" a fluent API; you need to understand how developers will need (and expect) to use your API. Here's a case study of what the design process for a fluent API looks like. In my previous ...
Validot is a performance-first, compact library for advanced model validation. Using a simple declarative fluent interface, it efficiently handles classes, structs, nested members, collections, ...
Abstract: The fluent API, also known as Internal DSL, is one of the concepts introduced primarily for the purpose of increasing readability and maintainability in the process of software development.