I'm actually asking this for something fictional, but just to be more believable, are there any animals that could at least spend a given amount of time with a fox, and not be in any risk, or be any risk to the fox? If there aren't any in real life, are there any that you think could believably be used for this in works of fiction? Like I say, the animal can't be anyone who is either likely to cause harm to a fox, or is likely to be harmed by a fox.

If the "make friends" part confuses you, that's more of a fictional device, as in reality they probably only "make friends" with other foxes, so it could also just be an animal that is mainly on neutral ground to the fox, and is neither food nor threat. Any help, would be greatly appreciated.