Weird. Why?
You have paid for them. There is no commercial use here, obviously. And if it weren't explicitly agreed before payment, you own them since those are your original characters and your original ideas.

1) they were gifts
2) unless you have documentation expressly signing over the copyrights to you as a user, fa will assume the original copyright still belongs to the artist.
3) while i own the copyright to my character, i do not maintain the rights to habe the picture hosted without the aforementioned signed legal document.

This is something I've seen play out between another artist and friend that i tried to set right, and even when i provided the tos and commission form from the artist to prove that the commissions my friend got fell under its right to jost policies, because it was a digital form, because there was no signature or official proof (that, even if there was, the artist could simply say they lost or could not find), the pictures still had to be taken down as per FA's policies, but even beyond FA's policies, legally they are bound by the current letter of the law.

I was asked to take them down instead of getting FA's moderation involved and I complied, because the result would have been the same.

Does this mean that any artist Can request your art be taken off of your personal FA page? Yes. For any reason? Yeahuh. Unless you have explicitly documented proof, yes.

Most artists see more benefit to their art being on your page as a way of generating more interest and business, and because the visibility of being seen removing their art from your gallery would possibly negatively affect people wanting to do business with them because of the possibility that their own commissions would be in a potential state of jeopardy.

But it is a right afforded to them by the letter of the law, and thus, also by FA's policies, who have it in their best interests to protect the artists that contribute to FA's popularity and usage.