Reflection has proved to be a powerful feature to support the design of development environments and to extend languages. However, the granularity of structural reflection stops at the method level. This is a problem since without sub-method reflection developers have to duplicate efforts, for example to introduce transparently pluggable type-checkers or fine-grained profilers. In this paper we present Persephone, an efficient implementation of a sub-method meta-object protocol (MOP) based on AST annotations and dual methods (a compiled method and its meta-object) that reconcile AST expressiveness with bytecode execution. We validate the MOP by presenting TreeNurse, a method instrumentation framework and TypePlug, an optional, pluggable type system which is based on Persephone.