Although he was strangely attracted (not sexually; let's get that out of the way before the bad jokes start) to the likes of Gwok Jing and Little Dragon Girl, in general, Chow Bak Tung didn't like being around boring people. Other than the Ying Goo/Emperor Deun affair, Chow Bak Tung feared nothing except boredom. Little Dragon Girl aside, he doesn't associate with people he considers boring.
And then there is his student, Yeh Lut Chai.
The adult Yeh Lut Chai was a stiff. He was probably even more rigid about morality, propriety, and Confucian social convention than was his famously straight arrow (sorry, bad pun) father-in-law, Gwok Jing (and that really says something). Not likely that Chow Bak Tung would choose such a stick-in-the-mud as a student, but he did.
In ROCH '83, Chow Bak Tung alluded to the idea that when Yeh Lut Chai was a boy, he wasn't nearly so rigid; Chow mentioned an incident where the young Yeh Lut Chai shaved off all of a goat's fur just as a silly prank. In the Tony Wong ROCH comic book adaptation, there's a hilarious scene of the very young Yeh Lut Chai chasing after Chow Bak Tung with a huge pile of animal dung in his hands. That's quite a contrast from the dead serious adult Yeh Lut Chai we see in the main story of ROCH.
So what was Yeh Lut Chai really like as a boy? Was he really so mischievous? And why did his personality change so much? Sure, people do grow up, but such a radical personality change often comes from more than just natural maturation.