｢Every time you hurt me, you're hurting Chara, too.｣ If they're going to die anyways, they might as well make their death awful for her.
* “You’re already hurting them
…More than I ever could.”
Frisk’s words were meant to stab at her akin to the knives they’d wielded in all those prior timelines Gaster had told her about before the human had mysteriously chosen to ‘save’ them all; how they’d sometimes rampaged through the underground with nothing but dust and ash in their wake before seemingly resetting time to start over. Other times, they would single certain individuals out for death and spare all the others. Culling monsterkind was merely a game to them.
While Chara, the only human that the arethusae had ever given a damn about, was forced to watch.
Even now – their soul was somehow trapped. If she could not free them from Frisk, the least she could do was hope that they could rest once she killed them.
Regardless of the consequences.
* “Our freedom is just an experiment to you, just like our deaths.”
A spear is summoned to her grip and buried in the human’s chest.
It is a quicker demise than they deserve.