It's NC-17, and kurtbastian. it starts out as just sex, maybe they're at a house party together or something, and they go up to kurt's room and decide to have (oral) sex. sebastian blows kurt, but not before being very meticulous about consent, asking him if each step is okay before he does anything. kurt is impressed. before kurt can return the favor, they get interrupted. maybe someone is hollering for them? and/or sebastian has to drive someone home? anyway, eventually there's more sex. I think they're more attentive about safer sex, in that they use condoms for blowjobs (which is of course a good idea, but doesn't happen a lot in fic). I hope this jogs someone's memory! Thanks for the help!