Responses
Could it be this?
http://www.mangago.me/read-manga/fate_zero_dj_yoru_wa_sensou/
Could it be this?
http://www.mangago.me/read-manga/fate_zero_dj_yoru_wa_sensou/
I'm pretty sure it was a one shot and the only scene I can remember is the uke's getting fricked by some tentacles or slime or whatever and the other guy's like "dO I have tO watch?" And the uke's like "havinG a vOyeur geTs me hOt"
If u can find it from this shitty explanation I'd be very happy :)