Sweet! Glad we got that figured out, hahaha!

I think we have everything. But just to make sure we're on the same page, this is what I'm understanding:

The human kingdom is battling human and Yucuruna invaders. During the war, Knight leads a division of the army through Elven land to execute something of a surprise attack, despite not having been given clearance to do so. He and his soldiers are beaten back, him being the only survivor. As he's returning home, Elf spots him trespassing. They duel, with Elf being victorious and punishing Knight for crossing boundaries. When Knight returns home, he speaks to his king about training under the elf. Human and Elven Kings discuss opening trade and boundaries, as well as enlisting Elf as a teacher for Knight.

Elf reluctantly takes Knight as an apprentice. At first he's cold and terse, but grows warmer after Knight shows himself as a quick and competent learner. Their relationship builds from there until they are close friends. At this point it's time for Knight to be returning home, but both of them try delaying the departure until they can think of a way to keep together/in touch.

Is that right? I think that's everything we covered, but I may have forgotten something!
Also, I was thinking about when the romance would begin to develop? From what we've got so far, I was thinking that the knight was probably smitten with the elf since they first met, but you may have thought of something else.