Rule 34 Dev - 2d alternate_universe animated_skeleton blowjob blush fan_character fellswap fellswap_sans ghostskeleto heart male male_focus male_only mettaton mettaton_ex monochrome oc original_character rule_63 sans sans_au sans_oc skeleton small_sub_big_dom sucking_penis tagme undertale undertale_(series) undertale_au yaoi|8394412384