A fox is possible and wonderfully rewarding but is a long term thing not just a one night stand, I have a fox that frequents our garden and it started with food and water and when the nights got colder it was bed and warmth, she trusted me and I asked her, she allowed me and now she is a regular visitor, the issue is that it may have been at a detriment as I have never heard her call for a mate, she only calls in the house so whilst it is possible, it is not recommended as now there may be no more foxes from her