If—for some reason—they were able to knock Twilight out, they would go into her mind and find two versions of her Filly version being ridiculed by a shadow version of herself. They try to protect Filly-Twilight, which in turn gives her enough confidence to face the Shadow-Twilight by merging with it. This could explain why Twilight was being cynical to her friends, brother, and mentor; the shadow version was a very dominant personality.
WMG / Bitterness
The fic will later take place in Twilight's mind.