"They bumped into each other on a day where there was much radiation streaming from a lot of sunspots on the sun. All that radiation caused a bunch of “molecular instability” which particularly affects their magic. Sabrina assumed she wouldn’t be affected since she’s half-mortal, but she did get affected nonetheless when she bumped into Libby in the hallway at school, causing Sabrina’s goodness/virtues to get transferred to Libby while Libby’s evilness got transferred to Sabrina."