Although it's been almost a week since Twilight changed into an alicorn, she can still feel the consequences of her decision echoing. Strange things begin to happen around her, and it may be up to Spike to figure out just what's happening, and what Celestia failed to explain to Twilight the very first time they met.
Meanwhile, Twilight struggles against her developing darker self, trapped in in her own mind until her antithesis is banished, or she is.
Picture credit goes out to turbosolid on deviantArt.