Definition of "Wincest"

Wincest stories often take their transgressive cues from the text itself; often when Sam and Dean are seducing each other in Wincest stories, the more reluctant of the two is convinced to engage in the relationship when the other reiterates that they are already outsiders in society, already isolated from the “normality” of their world—why should the prohibition of incest stand in their way when they have already broken so many other laws?

2009, Emily Turner, "Scary Just Got Sexy: Transgression in Supernatural and Its Fanfiction", in In the Hunt: Unauthorized Essays on Supernatural (ed. Supernatural.tv), BenBella Books (2009), page 159

Instead, she suggests, the romanticized, paratextual Wincest slash fiction offers Sam and Dean a redemptive happiness that they are perpetually denied by the show's writers both in a diegetic sense (via Chuck Shurley, the show's writer/prophet who publishes novels based on the boys' adventures) and in a non-diegetic sense (via Eric Kripke, Sera Gamble, and the show's returning writers).

2011, Darren Elliott-Smith, “'Go Be Gay for That Poor, Dead Intern:' Conversion Fantasies and Gay Anxieties in Supernatural”, in Stacey Abbott, David Lavery, editors, TV Goes to Hell: An Unofficial Road Map of, Supernatural , ECW Press, page 106

Supernatural fandom features some of the more controversial iterations of slash, predominantly Wincest (the incestuous coupling of the show's protagonists, the Winchester brothers), […]

2013, Henry Jenkins & Suzanne Scott, "Textual Poachers, Twenty Years Later", in Henry Jenkins, Textual Poachers: Television Fans and Participatory Culture, Routledge (2013), page xxxiii