This is pretty much "Explain a movie plot badly" for Fire Emblem, except it's not just limited to the overall story. It can be about supports, cut-scenes, story events, gameplay, etc.
For some examples:
King creates decades long conspiracy, escalates a minor conflict into a continental war, and ends up sacrificing his life, all to get rid of one insane person.
Man turns food testing event into a diplomatic marriage proposal to aid with race relations. Woman licks his eyes.
A rabbit, a candyman, and a historic cosplayer all join army on the spot to prevent assassination attempt.
Desperate heroes go back in time to the previous generation to prevent a zombie apocalypse. End up fighting in a different conflict entirely.
Priestess goes on pilgrimage to the main temple of her goddess. Accidentally eradicates criminal empire along the way.
Calvary kill ten attackers by standing still in a corridor.