By u/Rodoran, its an unhinged shower-thought comment on Lung from Parahumans being gay and is a power bottom.
Lung, was a terribly repressed homosexual. He wanted desperately to be a power bottom, but every time he met a sexual rival, he would turn into a dragon, and thus suddenly become a top.
His closest sexual encounter was during the fight in Japan, vs the Endbringer Leviathan. Unfortunately, every time he was about to be 'taken', he would strengthen further. First came the second set of limbs, then wings, then his scales hardened to a degree that even legends lasers couldn't penetrate.
Sadly, if Lung knew better, he would have absolutely let Legend penetrate him. He was however, a bit busy due to the giant Endbringer, so he wasn't able to satisfy his sexual urges.
The stories tell of Kyushu and how it sank that day, but the stories often tell a lie. The heroes don't want the truth to get out, and almost every villain attending died or drowned in the chaos that followed.
Cauldron(who you don't know, and have never heard of, if you god damn know what's good for you), made sure the story was about the heroic growing dragon man, fighting the terrifying water Godzilla, both going at each other until the island sank.
The truth was, though, after being spanked for 8 straight minutes, Lung's errection was large and powerful enough to completely crush the island. Thousands of heroes(including independents and villains, because everyone is a hero during an Endbringer battle) died due to his massive, draconic throbbing cock, which tore the land asunder.
The reason Lung was allowed to leave, and eventually settle in Brocton Bay had nothing to do with his perceived power, it was simply down to a moment after the battle where Alexandria side eyed both Legend and Eidolon, and whispered "holy shit, dibs"
And this, the legend of Lung became something told to children everywhere, how he was feared, and not someone to fight. Parents, of course, ones who knew the true story, did not tell their kids.
Because of this information failure, one night in the middle of 2011, a teenage girl who hadn't picked a name yet, would unintentionally challenge the dragon, and she would, also unintentionally rot off the world's largest penis. This would have reprocusions that would last until the battle with Scion himself, but that's a story for another time....