https://www.mangago.zone/read-manga/spilled_blood/
How about this one
https://www.mangago.zone/read-manga/hitorijime_my_hero/ not guardian but he takes care of uke
https://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/
https://www.mangago.zone/read-manga/my_sweet_home/
https://www.mangago.zone/read-manga/his_little_amber/
https://www.mangago.zone/read-manga/nakanai_hibari/
https://www.mangago.zone/read-manga/kusuburu_kemuri_no_nare_no_hate/
https://www.mangago.zone/read-manga/eternal_flight_of_the_gull/
( Not really a guardian)
Looking for manga where uke has a crush on his older stepbrother seme (not younger please!) or perhaps guardian seme who took care of uke since childhoo.
I read Super Lovers ages ago, but I'd prefer that the story starts when uke isn't too young.
Other examples are: Koi Nanka Shitakunai by Tsukimura Kei, Kami-sama No Iutoori by Moegi Yuu.