Here's a Sketch of Vluxen depicting all different organs he has, well, not all but his digestive and his brain
About the Alternarian gem, it's a crystal that is within an alternarians brain, and it essentially helps hold their body together as an Alternarian is made of mostly magic, until Vluxen was created no one has been able to make a Chimeran (A constructed sentient race made from different parts, usually using a demon body or soul as a base) with a Brain gem without the result being a sad puddle of flesh, all conventional means of making a chimera with a brain gem would not work, until an Alternarian woman dabbling in this craft tried growing a Chimeran within an egg rather than a vat, it took years and years, she gave up on the project, but Vluxen was born from the discarded egg that was unknowingly a success.
The mixed organs are why he needs pills to properly eat, but also are selected to make him an incredible mage! especially with storm magic.

[EDIT: I forgot to mention his fur coloration comes from the variation of demon called "void blasters"]