>>536705695
Alright, prep a save. This will be a reverse of Undertale, so to AVOID fulfilling the prophecy, you will have to do specific actions to put the game into "neutral" route, instead. Gerson told you that answer may lie "somewhere in the middle".

>collect Shadow Crystals (obvious)
>and Eggs
>get and keep ThornRing - start Snowgrave, then abort at Berdly
>max out Susie's heal in Chapter 3 AND 4
>get ShadowMantle, it is the "weird" portion of Chapter 3, it will likely come up in the future