Being both approachable and a long-term resident, Ami might have been the first person that Amity stayed with after she decided to give up trying to keep her own house and go live in someone's wall like a civilized rodent? I'm thinking she started out at Ami's and then went and lived at Rook's for a while and now she's at Iogann's.

Anyway, any time Ami needs something with tiny moving parts fixed, Amity's only too happy to help out.