Years, decades, and centuries had passed since Birlach last fought in the last great war. In fact, over a decade had passed since he had fought anyone at all. Last several years, he had solely focused on running his school, where he was teaching his many apprentices. Initially, he had intended to leave the teacher role and go deep into the mystical arts to learn as much as he could, but when he got the chance to take over the school he once studied at under the great magician Ólafur, he couldn't refuse.

This story began during the first Era, around 200 years after the battle of Kadesh, where Birlach played a central part. One sunny morning during a particularly warm spring, he was sitting in his outside office working. Suddenly a colossal crash could be heard from the castle where his school was located. Within seconds Birlach was up on his feet, running towards the school. When he approached the grand gate at the front of the school, he could see smoke coming from one of the windows on the east side and many apprentices welling out from the castle.

“What in Odin’s name was that?” Birlach asked the first apprentice he got to. “Someone managed to blow up the laboratory, sir,” the apprentice answered. “Do you know who it was?” “Sadly, I do not, but I believe I heard Babish talking about him having been on that floor when it happened,” they answered and pointed toward one of the apprentices standing in a ring closer to the school.

Birlach approached the person they had pointed out and started inquiring for more information. It turned out that the apprentice at fault was Brynjol, a student Birlach knew who had a history of messing around with stuff he shouldn't. At that exact moment, like magic, Brynjol walked out through the gates while the other apprentices looked at him. Apparently, the rumor of the source of the ruckus had spread fast. Birlach waved to him and asked him to come over.

The two of them took a walk around the small lake that was situated by the school. “What exactly happened?” Birlach asked. “I am so sorry, Sir. I just wanted to test some of this new battle magic I found in an old scroll. I know I'm not supposed to.” Brynjol responded. “Most certainly, you are not. You know this. This is the 5th time you blow up a whole room because you were testing some old battle magic.” Birlach said back. “This is the last time. You knew this was your last chance.” “BUT, SIR! You have to give me another chance. Please…” Brynjol screamed back.

Birlach did not give him another chance. He packed his bags the next day and was out of the castle before lunch. From his residence in the southeast corner tower, Birlach watched as Brynjol walked down the path through the trees and away from the school. “I have a feeling… That was not the last time I saw him”.

Seasons, semesters, and decades passed. Two whole decades had passed since that spring day that Birlach expelled Brynjol. They had not met each other all that time, but they had heard of each other. Birlach had kept teaching at his school, and Brynjol had dwelled further down into the many scrolls about ancient battle magic. A morning that wasn't far from that spring morning twenty years ago that all changed.

Birlach was sitting in his new office in his school's newly created south annex. Suddenly the door to the room flew open, and in walked a face he had not seen in many years. It was Brynjol. “Hello, Brynjol. What can I do for you?” Birlach asked him. “How dare you speak to me, you old old weak sad excuse of an archmage.” was all that Brynjol said in response. “Oh… here for revenge, are we?” Birlach asked him. “You bet your arse I am. I am going to kill you.” “No… You are not.” Birlach said and stood up from his chair. With a snap of his fingers, Brynjol was now kneeling over, screaming with pain.

“BUT HOW?! All these years… how are you still stronger than me?” Brynjol asked in disbelief. “I don’t think you get it,” the archmage said to his traitorous student. “I didn’t give up the sword because I am only good at magic or frail and weak. In fact, I was too good at it, and that bored me.”

This is the first time I write something for r/writingprompts. I kinda like some of the parts of this story. Might add it to the bigger universe I am writing.