Cheoreomneun Nagwon

Seo-Won, who has been a beta all his life, suddenly experiences a heat cycle when he manifests as an enthusiastic omega one day. Because of this, he ends up spending a night with her stepbrother's son, Yo-Han... Unlike Seo-Won, who tries to pretend the 'accident' never happened, Yo-Han gradually reveals his hidden obsession.

"I like you, Uncle."

(Source: Mr.Blue, translated)