First of all, "Pillar" is from Magic Knights Rayearth. The term for pure Utena would be "Rose Bride" - who is tied in some very strange and mystically potent ways to the Overarching Mystic Constructs of Ohtori Academy and...
Really, the thing to know is that Utena is a mindwarp on grand scale. The look may be BESM, but the feel is more a Changeling variant. At one point Utena defeats an enemy and he ceases to exist, in that retroactive, "no one can even recall that he ever was" sort of way - and it makes a fair amount of sense with respect to the show. The entire thing is submerged in symbolism and metaphor, to the point that you sometimes have to look back more than once to figure out how much of it was real.
To put it another way, Utena is one of those shows that you *really* need to watch for yourself before you can fanfic it well. If that is absolutely not an option, and you *must* write Utena fanfic, then at the very least read up fully on the wikis and read a lot of single-source fanfic by different authors. If your only understanding of it is through UF, then don't use it at all. Even without the infection from outside and huge warpings from author perspective, the UF version is fused inescapably with Rayearth, and twined heavily around a cosmology out of AMG. UF as a source will not serve to help you do anything but write UF fanfic, and no one wants that (particularly not the core UF writers.)
Really, the thing to know is that Utena is a mindwarp on grand scale. The look may be BESM, but the feel is more a Changeling variant. At one point Utena defeats an enemy and he ceases to exist, in that retroactive, "no one can even recall that he ever was" sort of way - and it makes a fair amount of sense with respect to the show. The entire thing is submerged in symbolism and metaphor, to the point that you sometimes have to look back more than once to figure out how much of it was real.
To put it another way, Utena is one of those shows that you *really* need to watch for yourself before you can fanfic it well. If that is absolutely not an option, and you *must* write Utena fanfic, then at the very least read up fully on the wikis and read a lot of single-source fanfic by different authors. If your only understanding of it is through UF, then don't use it at all. Even without the infection from outside and huge warpings from author perspective, the UF version is fused inescapably with Rayearth, and twined heavily around a cosmology out of AMG. UF as a source will not serve to help you do anything but write UF fanfic, and no one wants that (particularly not the core UF writers.)