I bring a sort of "I love Gwyn" vibe to Gwyndolin tag that no one likes.
No but like, I get if one sees that Gwyndolin was oppressed by Gwyn and all, I myself feel related to the fact Gwyndolin was raised according to his father's will since I'm asian 💔 and even though it's explicitly said Gwyndolin loves the sun thus his father, and his whole environment in DS1 bla bla, I agree that an abused child can still love and devote to their parents out of filial piety (source: me).
But hey, Gwyn actually never hid Gwyndolin away! Like if a Fromsoft monarch wants to hide their hideous child you will know it *pointing over the direction of a certain goddess*, but Gwyn:
- allowed the moon cult, made them his police department
- let Gwyndolin be the patron deity of Oolacile, with his statues everywhere in that place, particularly around the Battle of Stoicism arena which is the place where people fight to gain the rights to Anor London (screw the God of War anw amirite). There's even Gwyndolin's statue in Ringed City
- the parchment behind Miracles in Dark Soula actually depicts Gwyn and Gwyndolin (screw the Firstborn amirite) ever since DS1. DS3 just upscale the quality so we can see it better
- "Gwyn hates Gwyndolin because he has moon power" have you seen the way Gwyn treated the original of that moon power. Seath was given his own land in the highest place of Lordran, was allowed access to every knowledge ever known to gods, was allowed to have servants that go anywhere they like and kidnap maidens, was wed legitimately into Gwyn's family himself. And with how powerful the Dragon School of Vinheim and how much widespread sorcery is, it's pretty safe to say Seath was allowed to spread his influence in this world too
- "Gwyn hates Gwyndolin because he is half-dragon" Shira, someone was also half-dragon - highly implied to the legitimate child of Seath and his rightfully consort that Gwyn gave him - was given Knight title, was the closest servant of a child of Gwyn, likely participated in the dragon war (she used miracle of female dragonslayer and dragonslaying is said to be "Knighthood's highest calling" in Lordran), was allowed to execute a whole Pygmy Lord, and utterly loyal to Gwyn and was proud of her lineage. Safe to say she suffered no oppression from him.
So no, Gwyndolin's existence was not something hidden by Gwyn, if he actually did it we will know (cue Filianore and Ringed City, hell Filianore is implied to even got her name changed since it's Latin instead of Welsh and it means Daughter of the Sun, which likely is what the pygmies call her instead of her real name), it's just Gwyndolin being extremely self-conscious. And if this self-consciousness self-inflicted or cause by Gwyn, well that's your own headcanon, I have no say in that 🫡