Currently crying about Yoso-Tama-No-Kakehashi, a Japanese guidebook from the 1700s about raising rats. It's the first known rat guidebook in the world :)

They were raised as pets and for show animals, and it's mentioned in the guidebook that "one can call out and rats will come to hand". They were referred to as "nezumi" and it was considered important that they have large cages to live in. There was also a variety of rat that had a fox-like coat!

Rats were domesticated in Japan from the 1600s to the 1800s - it's unknown if any of those domesticated strains are ancestral to the current domestic rats today. They were domesticated again in Europe in the 1800s (initially for much crueler reasons than just for being pets) and I think it's just so sweet that we as humans fell in love with rats so much that we had to domesticate them at least TWICE...

You can download an article about the guidebook here. https://www.google.com/url?q=https://www.jstage.jst.go.jp/article/expanim/60/1/60_1_1/_pdf&sa=U&ved=2ahUKEwioidaLs5z6AhUojIkEHRI1BvEQFnoECAkQAg&usg=AOvVaw3aarTW0iy1HybCcrxtp4ww