She's not supposed to exist. She was never supposed to exist, especially outside the fabrications of the computer server. That becomes all too evident as the world around her is drained of all color and life. The closer she approaches something, the more her presence drains from it. It started with Princes Twilight being absorbed into her, then the books, the furniture, then the entire library. The unicorn can't control any of it; like a black hole, her body sucks up everything it can grasp, from the earth she stands on to the people and buildings around her.

All she can do is run and leave destruction in her wake, but this world, this universe, was being taken into the pony, not entirely unlike the alicorn who brought them all here. Unlike the faux Pale Pony, she wasn't after knowledge; her genetic code sought purpose. Those never meant to exist have no purpose, but how can she survive as a Twilight if she can't exist? Absorbing the real Twilight wasn't enough for her body, so when her possessions and her home weren't enough, it pulled in everything it could reach. Consume enough matter from things in this plane of existence and she'll have her own existence...that's what her genetic code concluded. And that selfish survival instinct would rob Twilight of the willpower to live, even after sustaining her life.

She can only run and hide for so long. All of existence will be pulled into her and there's nothing she can do to stop it. She's a virus, contaminating this world and taking it down with her. It'd have been much easier on everyone if she simply stopped existing...