So..Small Brooke didn't just get corrupted. Like…Apart of her corruption was emotional related but..Here's the twist, the cause of her corruption being permanent was thanks to mutagen or "Ooze" that the survivors from the mutagen bomb call it, splashed onto the poor mare in an accident while she was armed, having came out from Stable 27 at Viewpoint, after spending many many years underground. But once she mutated and permanently became her corrupted self, she never returned back and resides in an abandoned house where she survives and all. Here…She seemed to have been found by some mutants as they approach her.

And the green arteries, that's mutagen running through her. So her blood is mixed with this chemical.

So yeah…I decided to do a fake screenshot here, hence the reason there's no watermark.