Marth makes you an offer

Notes:

Context

The DS remake of Fire Emblem: Shadow Dragon had this weird gimmick where side chapters referred here as "Gaiden Chapters" were only unlocked based on how many units you still have alive. If you're under a certain number, you unlock the gaiden chapter after clearing the main chapter, and you recruit an extra character from that map to make up for your shortcomings. If you're competent or you always reset whenever a unit dies, you'll never get to see those gaiden chapters. Alternatively, you can always intentionally kill off your army to unlock the gaiden chapters.