Foxes are very cute animals indeed, so why not to tame a fox for yourself as a pet? Foxes is wild creatures, it is rare to see them as a pet in reality, but you will be able to have such pet in Minecraft. The idea of creating the addon came up simply by the fact you can tame wolves and cats, but not foxes.
Find Sweet Berries and give them to a wild fox. It may not work with the first fox you find, so try several ones. Foxes will be behaving just like wolves – you can even command them to sit.