Multiple persons in one body
Multiple psyches/souls inhabiting the same body
A special instance of soul migrations etc., but the dual (or multiple) inhabitance in the same body permits the author to engage characters in cross-gender dialogue; verbalize their gender dysphoria; comment on the other person's experience or their own experience of the other person's body; show blended gendered experiences (as in sudden bisexuality). May also be handled as a form of demonic possession, spirit possession, or past life recollection/possession. May also be treated in a non-SFnal (or ambiguously SFnal) way with MPD, multiple personality disorder.
- Frank Herbert, Dune series -- character Alia and indeed other characters who cannot handle absorption of ancestral memories
- Robert A. Heinlein, I Will Fear No Evil
- Tanya Huff, Quarters Series
- Matt Ruff, Set This House in Order
- "Born Again", The X-Files episode (1x21) - A transgender partial reincarnation / possession. A murdered male policeman is reincarnated into the body of a little girl. Notable for its non discussion of gender issues.
- Lynn Flewelling's The Bone Doll Twin , Hidden Warrior, The Oracle's Queen