You're in the Nether looking for ancient debris when suddenly you see something in the corner of your eye that looks like a tiny dried-up Ghast. You feel bad for the poor thing, so you take it back to the overworld with you and rehydrate it. After a while, you start to see a smile form! When eventually, it wakes up. It starts to fly around, looks at you, and clings to your side, thinking your it's momma. It starts to make almost baby-like sounds.