Mindtrap

Set in season 3, Lotor has become the greatest threat to Voltron, and Lance continues to question his place on the team.

During an attack on Lotor's forces, the paladins make a fatal mistake and are forced to leave Lance behind, trapped on the Galra battleship.

Captured and consumed with regret and bitterness, Lotor and the powers of one of his most dangerous hybrid generals succeed in turning Lance into a weapon against Voltron, determined to seek revenge on those who had abandoned him.

Langsty, and there's Klance too I swear