Ally Support is a feature in Fire Emblem Heroes that allows players to form partnerships between their units. Supports can rank all the way up to S rank where a cutscene showing the two units blushing together plays (as seen here). This can be done with any units regardless of gender.

LGBTQ references in this game series:

Fire Emblem: Thracia 776 (1999): Marty and Dagdar

Fire Emblem: The Blazing Blade (2003): Bramimond; Florina and Lyndis; Legault; Lucius and Raven

Fire Emblem: Sacred Stones (2004): Ephraim and Lyon; Joshua and Gerik

Fire Emblem: Path of Radiance (2005): Ike and Soren; Jill and Mist; Reyson and Tibarn; Sigrun and Tanith

Fire Emblem: Radiant Dawn (2007): Elincia and Lucia; Heather; Jill and Mist; Joke about Ike and Sothe; Kyza; Ranulf

Fire Emblem Awakening (2012): Gay Jokes and Queerness; Same-Sex Relationship Hack; The Hubba Tester

Fire Emblem Fates (2015): Forrest; Nina; Romance options; Same-Sex Relationship Hack; Skinshipping; Soleil; The Hubba Tester

Fire Emblem Echoes: Shadows of Valentia (2017): Leon; Lukas; Queer Readings

Fire Emblem Heroes (2017): Ally Support; Loki; Sharena

Fire Emblem: Three Houses (2019-2020): Byleth Pairings and Controversy; Non-Byleth Pairings

See also QRM’s entry for this game series

Citations:

1. Dafg. (2020, May 12). Flying Bois get married. Retrieved July 27, 2020, from https://community.gamepress.gg/t/flying-bois-get-married/74736
2. MannyKunV. (2017, September 6). Fire Emblem Heroes – Spring Lucina and Camilla Max Ally Support. Retrieved from https://www.youtube.com/watch?v=UqKvPNfXHP4
3. Various. (n.d.). Ally Support. Retrieved July 27, 2020, from https://feheroes.gamepedia.com/Ally_Support