Appears in story chapter 2-7, when a cat the young master was taking care of decided to form a pact with him.
She was very shy and ran away several times out of embarrassment. Frej tried to take these opportunities to recruit her, but she ended up back with the young master in the end.
Mona named this Child after Freyja, the goddess of love, for one simple reason: her pact was made for love.
Since Freyja comes from a cat, she still sometimes mews at the end of her sentences, and has been known to call Mona "Meowna."
At times, she wanders off unanounced, but we know now that's only because she's off visiting her pactmeowker. Er, pactmaker.