An idea that sprung up on tumblr, involving Harmony. What if the plundervines drained her to the point they forced her to transform into a more corrupted version of her pony form, as if the vines themselves possess her and use her as a vessel to spread more chaotic influence throughout Equestria.

Harmony can't do anything but let the vines control her like a puppet, but her awareness is still her own. She can only hope that her Bearers can save her from this corruption and restore order before it is too late.

In the rp side of things, this is what Harmony is thinking of making herself for Nightmare Night. XD