User blog comment:DarkClaw3/PE Proposal: Cosmos/@comment-31647719-20191129031358/@comment-1705775-20191129035332

no, Mephisto claims to be evil personified, as do many other demons but outside of D&D style settings (where they are treated as beings literally made from chaotic, neutral or lawful evil) demons have free will and often they are modernized as alien / extra-dimensional beings who play on the idea of devils etc to either excuse their horrible nature or play with mortal fears of such.

to be made of evil is to be a conceptual entity from "birth", akin to being an elemental, unable to change what one fundamentally is - Discord has shown that his species are a little more complicated than that.. for example Discord made a choice to stop being quite so destructive with his chaos and befriend the cast, he also at one point tried to stop being chaotic altogether (that, however, did kind of backfire as his kind still require *some* chaos to exist).. but a well-balanced Discord-ian is a fully morally flexible being.

Thus with all that in mind she is just a reality-warper who fancies herself being the "Devil" rather than actually being evil itself.