anal anthro anus bodily_fluids butt cum duo genital_fluids genitals human_on_anthro interspecies light-skinned_male male mostly_offscreen_character penis precum solo_focus undertale_(series) vein veiny_penis asriellover undertale undertale_yellow asriel_dreemurr asriel_dreemurr_(god_form) bovid caprine goat human humanoid mammal hi_res