Thank you for asking!! From Kuroshitsuji my favorite is Undertaker/Vincent (or Undertaker/Vincent/Diedrich, any combination of them is PERFECT), then I have Emil/Lalli from Stand Still Stay Silent, Kabru/Mithrun and Falin/Marcille from Danmeshi, Kanda/Alma from DGrayman, Frankenstein/Raizel from Noblesse, Zhongli/Xiao and Kaeya/Dain (Kaeya/Albedo as well. Maybe with Dain too) and Xingqiu/Chongyun for genshin, Dimitri/Felix and Hubert/Ferdinand for fe3h, Lelouch/Suzaku for CodeGeass, Momo/Yuki for Idolish7, Gilgamesh/Dantalion for Makai Ouji, Marchen/Elisabeth and Shaytan/Layla for SoundHorizon, Athy/Lucas from WMMAP aaaand I'm probably forgetting so many - like book ones or tv series but these are the one I look for the most (overall, if there's a power dynamic just assume I like it. There's also enstars but I Will Not Elaborate cause the fandom scares me) If there's any series in particular you're curious about just ask!!