Two hedgehogs who mainly encountered and had an influence on Dr. Eggman in the original FNaS.

The first caused the bite and trauma.

The second... a fatal wound and not giving a choice for the Spirit of Doctor, but making him to possess a husk of Golden Sonic and live in the body of the worst enemy, which earlier caused the bite.

Fun Fact and Spoiler Alert:
This also has a connection to Silent and a plot in Fierce Forces.

One is her favorite, that regrets causing an accident (Origin Sonic "Midday-Up!")

While other one, is an opposite... Who has rethinked about his deed, but still wants to do a terrible thing (Salvage Sonic "Gory-Up!")