From what I know of Gaia, as long as it's not x-rated material (rape, incest, torture in extreme detail, etc.), it should be fine. Keep in mind that it's a PG13 site, so it'd be a good idea to use that as a guideline to what content you could post. However, you could put a tag on the summary or in story warning that it has mature content such as [list content here]. I did that with my arena entry and it seemed fine, (although to be fair, it never got to the graphic parts).
The Gaia ToS and the arena rules might go over what's allowed in more detail.
If you're really worried about it, though, I wouldn't mind looking it over. But this may be more suited to a mod.