As Samus see the last metroid egg, the baby metroid hatches from it's egg and imprints on her and think of her as it's mother. Samus, at first, was going to shoot it to exterminate it. But she couldn't kill the Metroid hatchling and spared it's life. Thus, sets the events of Super Metroid.

#metroid #samusaran #samus #hatchling