Tirek eventually learns how to steal magic after visit's with his former mentor Sendak in the mines. Even though Tirek betrayed him his mentor agreed to continue teaching him in exchange for his freedom. Tirek absorbs his father's magic rendering him weak and powerless and forces him to hand over the kingdom and makes his mother agree for the sake of her husband. Having no choice they agree and Tirek becomes the new King. Unfortunately he doesnt hold his end of the bargain and imprisons his father and refuses to free Sendak as he has outlived his usefulness. He makes sure that Scorpan doesnt know of what he did as he believes his brother could be of use to him. Tirek becomes Lord Tirek and his next goal is to travel to Equestria with his loyal brother to conquer it after stealing enough magic to become unstoppable. We all know what happens next.