There seems to be no law in the Philippines governing particularly the so called "Fan Art". Although others say that the Provisions of Republic Act No. 8293 otherwise known as the Intellectual Property Code of the Philippines and other related laws may be made applicable on such matter as it may be considered a "Derivative Work" being an artistic creation itself, hence, it may infringe the original derivative work which served as its inspiration.

My personal take on this matter is that, everything boils down to the fact that  although there are laws regulating one's "freedom of expression", an "artwork or artistic creation" knows no boundaries. And although these artistic creations  or artworks may be protected by law, one cannot be said to be infringing another's artwork by making the latter as an inspiration for "another artwork" which by the use of our senses could be determined as entirely different from the other. Especially because fan art are normally used for personal purposes as a fan of a character or an art and not for commercial purposes.

But what about if such fan art is being used by the artist for commercial purposes? Then I guess, it would depend  on people's appreciation based on the existing applicable laws of that particular fan art as to whether it is infringing or not. Because in that instance, there may now be an intent on the part of the artist of somehow infringing an original artwork for his own personal pecuniary gain. Hence, such artist may be in bad faith and such act may violate the right of the artist or the owner of the original artwork which the latter should of course have a right of action.