Xbooru - 1:1 1:1 aspect ratio 2010s 2017 2boys 2d 2d (artwork) anal animated skeleton big dom big dom small sub bigger dom bigger dom smaller sub bigger male bigger penetrating bigger penetrating smaller blue blush blue tongue blush bottom sans bottomless bottomless male brother brother/brother brother and brother brother penetrating brother brothers digital media (artwork) doggy position doggy style position duo ectoplasm finger in mouth fingers in mouth fontcest grabbing from behind grey background incest larger male larger penetrating male male/male male penetrated male penetrating male penetrating male monochrome monster off shoulder orange blush papyrus papyrus (undertale) papysans partially colored penetration penetration from behind saliva saliva on finger sans sans (undertale) seme papyrus sex sex from behind simple background skeleton small sub small sub big dom smaller penetrated smaller sub smaller sub bigger dom top papyrus uke sans undead undertale undertale (series) video game character video games yaoi