People who have not played FusionFall might not get this picture. This is Buttercup when she lost her memory prior to the events of FusionFall. She does regain it, however, and in the mission "I'm still standing" you can inform the other PPG & The Professor that she's still alive, as they had feared the worst.

I haven't done this mission yet, but I will someday.

It's a shame there isn't a Belladonna Nano. That'd be cool.