What would a magic item that is a living "baby" dragon that a player wears around her wrist do?

DMing for my first major campaign and we are roughly 25 sessions in

Before we started, one of my players joked that she wanted a magic item that was a cute baby dragon that wrapped itself around her wrist like a bracer/bracelet and was setimes alive

I told her she couldn't have a dragon as a pet and we laughed it off, but secretly I took note

Fast forward to now and the party is in a city of magic that is governed by, in part, by an adult white ice dragon

This dragon is extremely friendly, loves mortal races, and is almost kind to a fault to the people of her city, and the party loves her.

Unfortunately, she is going to die. More specifically, the villains goal is to absorb the dragons life essence so that she can de-age herself and be young forever.

If the party manages to prevent this fate, the dragon will only be partially de-aged, and will be mortally wounded. It an attempt to save its own life, it will, as a small wyrmling at this point, bond itself to the same party member so she can protect the dragon while it grows and heals, becoming an artifact tier magic item

My only question: what should this do? I like the idea of it getting stronger over time as the dragon heals, but I'm not sure what effects would be right

The party will be level 8 when they receive it!