Have you ever have one of those dreams where everything looks totally normal, but, for a reason you can't explain, there is an immense sense of dread woven throughout? You go through the dream, walking through rooms or trying to talk to people, and the dread keeps building. Then one little odd thing happens, something that would otherwise be simply strange, or amusing, or maybe even cute if taken in the right circumstance. Then all the dread breaks loose into a full on scrambling wailing panic, and the dreamer wakes up very loudly.
You ever have a dream like that? That's what this reminds me of. The moment of the dawning of pinnacle fear.
King Sombra came back, and used his dark magic on Pinkie Pie, banishing her to a realm of darkness and shadow, to be alone and miserable forever.
Desperate to get her friend back, Twilight delved into the most powerful and arcane of Alicorn magics, with the aide of Luna, she learned the Eye of Majesty spell, which allows the wielder to see all things.
Now, years later, Twilight has finally found Pinkie, who has long ago lost all hope and light trapped in her dark world, Pinkie is horrified at the lengths Twilight went to find her, but Twilight is shedding tears of joy, knowing she will be bringing her friend home and it was worth any price.
They were playing hide-and-seek and Pinkie walked up to Twilight and started being silly whilst Twi was counting and became surprised once Twilight opened her completely natural and normal third eye. Pinkie then proceeded to call Twilight a cheater and Twilight started crying because she just thought Pinkie was a vicious murderer and opened her eye in fear.