Having a second, younger minotaur around is a distinct embarrassment for Minos.
So the old maze-builder upgrades the basement: its walls shift now, its floors sink and elevate, and it’s largely impervious to yarn-based attacks. The guards prod its new inhabitant in and lock the gate.
He gets to the center eventually (put your shoulder to the wall and walk). He and his brother stare at each other in the dimness.
“Hey,” says the junior minotaur.
“Hey,” says the senior.
“I’ve got a plan,” says the junior, and lifts his smock to reveal the labyrinth tattooed on his back.