3 ideas
Yu Yuan is a former Nationalist military cadet absorbed into the Chinese People's Volunteer Army. He is captured in Korea and held on Koje-do, where pro-Nationalist prisoners forcibly tattoo an anti-communist slogan on his belly to block his return to the mainland. He chooses repatriation anyway, for the sake of his mother and fiancée, and on returning is branded a disgraced ex-prisoner and loses his standing, his fiancée and his future.
The UN principle of 'voluntary repatriation' turned each prisoner's decision into a prize that rival factions fought to control. Nationalist and communist cadres ran their own compounds through beatings, murder, forced tattoos and loyalty oaths. Where organized groups control the bodies, food and safety of individuals, a formally free choice records who holds power in the compound, not what each person wants.
A regime that demands its soldiers die rather than surrender treats captivity itself as evidence of betrayal. Returning prisoners are therefore handled as contaminated goods, however loyal they stayed in the camps. The survivor's endurance is recast as guilt, which leaves them with no sanctioned place in either the enemy's system or their own.