Lana hadn't seen Lyle for two years prior to "The Trouble with Tetris." He had abandoned his royal duties to live on the world of Tetris. He didn't even know their father was missing in the Mirror Zone thanks to Mother Brain.
On Tetris, Lyle became a Keeper of the Sacred Square at the Chamber of Tetris. When the N Team arrived on Tetris, Gameboy saved the accident-prone, clumsy Lyle and brought him to Lana, who he didn't want to see out of self-embarrassment.
The N Team gave him a makeover and attempted to turn him into a competent fighter. Lyle wished to take his place as the rightful ruler of Videoland, but Lana felt he wasn't ready. Failing at proving himself, he fell into depression as Mother Brain stole the Sacred Square. However, with Gameboy's help, Lyle retrieved the Sacred Square and became a hero to the people.
"Deschain" is the most common surname used for Prince Lyle and his family in fan fiction; his surname is never given in the cartoon or the comic. This surname comes from Roland Deschain, the protagonist of Stephen King's The Dark Tower series, which Mark Moore was reading at the time that he was writing his Captain N fan fiction.