Prison

The Prison is a building and a mechanic in Fire Emblem if that can be built in My Castle. A unit with Hoshidan Capture or Nohrian Restraint can capture generic enemy units and send them to the Prison, granted it has been built. Unique characters or bosses may not be captured. A maximum of two units may be inside at once. There are three options to choose when visiting the units; Scout, Persuade, and Free. Scouting (bribing with resources) and Persuading (sending a character to speak with the captured soldier) will both lead to--if successful--the enemy in joining the player's side.

Selecting the Free option will release the enemy from captivity, leaving one of the two cells empty.

Trivia

 * The units captured within the cells have names of their own.