Versatile/Reversible/Vers: term used to describe a person who can be either a top or a bottom—typically in a same-sex relationship.
Switch: term used to describe a person who can take either the submissive or dominant role in BDSM play.
This list focuses on works that contain vers character(s). This includes works where a character(s) is shown to be vers but take on a fixed role within the main relationship. For works with versatile couples, check out my other list here.