Anasterian and Kael'thas (Warcraft)

"So help me, Kael'thas, if my nails were dry I'd spank you all the way to Zul'Aman!"
              ~Anasterian, probably

Next I should do one like this with Varian and Anduin

King Anasterian (Kael's father) ruled over Quel'thalas for three thousand years, and had kept it a small and isolationist kingdom until its forces could no longer hold back the Amani trolls; at that point he went on to solicit help from the humans of Arathor, and in return he reluctantly agreed to teach them sorcery. Thus came the origin of Dalaran and the Kirin Tor. 

(The following includes both canon lore and a few headcanons): I like to think that Kael'thas had been difficult for his father to deal with; he was probably quite sheltered while growing up within the suffocating confines of Silvermoon, and was likely interested in exotic creatures like the humans. He left to study at Dalaran the first chance he got, to his father's dismay-- and there he must have skipped classes a lot and danced on tables drunk at the Legerdemain Lounge; it wasn't like he came there to study in the first place, seeing as his skill at sorcery was likely far above that of the humans there. He never imagined his time to rule would come so soon, and the demise of Quel'thalas had sobered him utterly; in the life of an elf he was probably still quite young and not at all ready to lead his kingdom, but, as per his words in WC3, he had tried his best. He must have carried the guilt of his father's passing for the rest of his days.