From Wiktionary, the free dictionary
From comfort + fic, by analogy with comfort food.
comfortfic (uncountable)
- (fandom slang) Fan fiction read in order to make oneself feel better when sad, ill, stressed, etc.
1999 October 25, Red Valerian [username], “What About A 'Sick Fic Archive'????”, in alt.tv.x-files.creative[1] (Usenet):I'm in need of some comfort fic - as opposed to comfort food - and this genre seems to fit the bill perfectly.
1999 October 25, Wayward [username], “Re: What About A 'Sick Fic Archive'????”, in alt.tv.x-files.creative[2] (Usenet):Tucking up with a cuppa and some comfort fic…sounds wonderful to me.
2001 September 28, Charles Glasgow, “Re: FIC - Almost Paradise: 1/4 (W/X)”, in alt.tv.buffy-v-slayer.creative[3] (Usenet):Be warned, this is gonna be anything but pure comfortfic or mushfic. Or pure angstfic, for that matter.