During the time she is captured, Meemai stays with Kalas but returns to Xelha upon her rescue, prompting Kalas to grumble about how he was used for the creature's own ends.
Meemai can change its size at will, and although this is likely a trait of all Greythornes, nonetheless uses the ability to hide in the hood of Xelha's cloak most of the time.
At the end of the game, it bonds with the other Greythornes of the world to recreate the Whale.
In battle, Meemai is used by Xelha as a focus for her light-based magic attacks.
There is a decent debate within the fandom whether the creature is male or female, though to be fair, the characters don't seem to be too sure, either.