Looking for foster rat

I have recently had one of my two male rats pass away, and the other one is now on his own. Although I don’t want to get any more rats, my two year old that remains is still full of life and energy and I believe is becoming depressed because he doesn’t have any friends. I am looking to foster or take care of someone’s rat or rats if possible until my rat passes away. I tried looking for rats to foster through the spca however there aren’t any available right now. If anyone knows anything that I can do to help my rat please let me know