When Xiyao ascended to become an Earth Immortal, the Star Lord on duty warned her while she was on an assignment in the mortal realm: The Son of Heaven was undergoing a tribulation there. If she ran into him, she could lend him a hand, but she must not offend this important person.
Xiyao figured that meeting a great immortal was all down to fate. She wasn't even a Celestial Immortal yet, so who knew whether she would ever run into one?
So when Xiyao ran into a shabby scholar in the mortal realm who took a fancy to her looks and wouldn't leave her alone, she simply ignored him.
Later, after Xiyao ascended to become a Celestial Immortal, the great immortal who had once undergone a tribulation in the mortal realm promptly took her to his palace.
Taiwei: "Don't tell anyone what happened in the mortal realm!"
Staring at that face she knew all too well, Xiyao straightened in shock. "Your Highness, rest assured. This humble immortal promises to keep it secret!"
Taiwei stared at her suspiciously for a long while, still unconvinced. "From today on, you will work for me in the lower realm. You don't need to come back."
Xiyao stared in disbelief at the genteel scoundrel who would silence her by killing her. She clutched his sleeve, sobbing and sniffling. "You said such sweet things to me in the mortal realm, swearing you'd be devoted to me and never leave me. And the moment you got back, you sent me all over heaven and earth..."
The immortals: ???
Taiwei: "Stop clinging to me like that. Fine, I'll let you stay!"
Xiyao: "Great Immortal, I ran into a problem while on assignment in the lower realm. Could you help me?"
Taiwei gritted his teeth. "Fine."
Xiyao: "Great Immortal, I'm in trouble in the demon realm. Could you come help me put on a show of force?"
Taiwei: "Let go of me first!"
Theme: Don't underestimate a mischievous youth. As the saying goes, people can't be judged by their appearance, and the sea can't be measured with a bushel.