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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 duo ectoplasm finger_in_mouth fingers_in_mouth fontcest from_behind_position grabbing_from_behind grey_background incest intraspecies larger_male larger_penetrating male male/male male_penetrated male_penetrating male_penetrating_male monochrome monster monster_boy 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 sibling_incest siblings simple_background skeleton small_sub small_sub_big_dom smaller_penetrated smaller_sub smaller_sub_bigger_dom top_papyrus tumblr uke_sans undead undertale undertale_(series) unknown_artist video_game_character video_games yaoi

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 duo ectoplasm finger_in_mouth fingers_in_mouth fontcest from_behind_position grabbing_from_behind grey_background incest intraspecies larger_male larger_penetrating male male/male male_penetrated male_penetrating male_penetrating_male monochrome monster monster_boy 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 sibling_incest siblings simple_background skeleton small_sub small_sub_big_dom smaller_penetrated smaller_sub smaller_sub_bigger_dom top_papyrus tumblr uke_sans undead undertale undertale_(series)unknown_artist video_game_character video_games yaoi

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 duo ectoplasm finger_in_mouth fingers_in_mouth fontcest from_behind_position grabbing_from_behind grey_background incest intraspecies larger_male larger_penetrating male male/male male_penetrated male_penetrating male_penetrating_male monochrome monster monster_boy 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 sibling_incest siblings simple_background skeleton small_sub small_sub_big_dom smaller_penetrated smaller_sub smaller_sub_bigger_dom top_papyrus tumblr uke_sans undead undertale undertale_(series) unknown_artist video_game_character video_games yaoi