Help, my short cutie became a smoking hunk!

I don't recommend this manhwa as much, but it does fit the trope for those who don't mind a problematic short story. MC and ML are orphans who relied on each other growing up, and MC sells his body to afford ML a better chance at life. Now that ML is a doctor, MC prepares to step out of his life, but ML isn't willing to let him go.

The dragon MC takes on ML as a pupil so that he can ascend and become a dragon too. However, unbeknownst to him, ML is more than just a young-looking imugi.

ML only has the appearance of a child, and for a short time too. He gains power through sexually assaulting MC during his sleep. MC eventually discovers the truth and ensures ML asks for consent first.

MC hasn't gotten over his unrequited love for his married best friend. That guy's son, ML, is now giving him a hard time because of his resemblance to his dad and his forward advances.

The story is decent, but it ends before a deep relationship can develop.

Omegaverse. MC and ML grew up in the same orphanage. They promised to run away together, MC wasn't able to keep his promise; he spends the following years searching for ML. When they reunite as adults, MC doesn't recognise ML. Meanwhile, ML thinks MC abandoned him, so he forcibly turns MC into an omega and begins sexually abusing him. MC's worldview shatters upon learning the truth, but he consolidates ML's two identities and vows to stay together.