Help, my short cutie became a smoking hunk!

In the first arc, MC transmigrates into a novel where he's the abusive older brother of ML. Unfortunately, ML has mind-reading powers and sees through MC's acting. Instead of growing up to resent MC, ML falls for him and bides his time, ready to assert dominance when he's older!

MC loves to dote on his cute little nephew, but four years later his nephew has become a sexy man! MC can't handle this stark contrast, and ML works hard to be taken seriously.

Incestuous yandere. The younger brother used to be a quiet kid, but then he grew up to be taller than the MC.

ML is MC's angelic half-brother. Even though they weren't very close when they were younger, ML has always desired MC. Many years after MC cuts off contact, ML finds him again and drags him back to their shared past.

ML is a dragon who, in his infancy, took on the form of a child. The remote town he lived in spurned him, and he quickly falls in love with MC, the only human who has ever shown him kindness. However, MC still sees ML as as child, so ML uses his powers to age himself up physically.

MC becomes ML's adopted older brother early in childhood, and we get to see them grow up. In adulthood, MC cuts off contact and joins the army. He gets trapped in a time-warping dungeon but is soon reunited with ML, who reveals that MC has been trapped for ten years.

When ML and MC first meet in person, ML has just reached adulthood. Their relationship is tumultuous and MC forcibly cuts off contact. After a time-skip, ML has grown up even more, to the point that MC is noticeably smaller than him, but his obsession is still the same. Only now, as an adult, he has the means to make MC stay.

The story also features a crime plot involving significant family members.

MC once served as ML's personal tutor while on a mission to assassinate him. He's ultimately unable to bring himself to kill ML, and they meet again six years later when MC infiltrates the mansion again.

Guideverse. MC protected 9-year-old ML during a dungeon break, and has sworn to look after him after his parents died. Now ML has grown bigger, but he still acts childishly to get what he wants from MC, who's weak to his angelic face.

I haven't read this one, but the story begins when the red-haired prince is a teen.