To jaja!
For Gaster or killer who did you want choice?
(You need sacrifice one ewe)
-the Creator NovaFruity
The Creator: wellll.... both, because there are 2 Jaja for those 2 characters. For Gaster I use Science!Jaja, and for Killer I use the normal/classic Jaja. That's why it's difficult to answer. (By the way Science!Jaja is an anomaly, she is eldest than the classic, and she was supposed to be youngest.)
But if I, Creator have to choose, it will be Killer UwU
(By the way I have a Core!Jaja, based on Science!Jaja's story)






