Xbooru - 2010s 2015 2boys 2d 2d (artwork) animated skeleton big dom big dom small sub bigger dom bigger dom smaller sub bigger male blue eye blue tongue boots bottom sans box digital media (artwork) dominant dominant male domination english text footwear glowing eyes hair over one eye high heel boots humanoid robot larger male licking leg male male/male male only maledom mettasans mettaton mettaton ex monster nude penis pink boots pink eyes pink glans pink high heel boots pink tongue robot robot humanoid robotic penis sans sans (undertale) seme mettaton shoes simple background skeleton small sub small sub big dom smaller sub smaller sub bigger dom solid color background submissive text tongue top mettaton uke sans undead undertale undertale (series) unknown artist video games yaoi