Xbooru - 2010s 2boys anal animated skeleton bigger male bigger penetrating bigger penetrating smaller blush blush lines bottom on top bottom sans brother brother/brother brother and brother brother penetrating brother brothers clothed clothing collar comic comic page comic panel eli-sin-g english text fangs fontcest incest kolesjoie larger male larger penetrating larger penetrating smaller male male/male male only male penetrated male penetrating male penetrating male monster papyrus papyrus (undertale) papysans penetration sans sans (undertale) seme papyrus sequence sequential service top sex skeleton smaller male smaller penetrated speech bubble sweat text text bubble top papyrus uke sans undead undertale undertale (series) yaoi