The Formers are very tragic and uncommon types of broods who used to be humans, to be infected as a human is suffer a fate worse than the most brutal death. Such a fate is so due to the mental destruction and physical agony one experiences during the fast but horrific transformation. The most painful part is when your skull reconfigures into that of a pony's and rips out of your face before your skin recovers it. Formers are identified by their unique standalone personalities that somewhat reflect on their past lives despite near total memory loss. The Cosmic broken hivemind also doesn't help with this as it constantly keeps the broods of all types in a unstable mental state.
Notable Broods who are formers:

Twilight Sparkle[Head Biologist Star Dawnson]
Pinkie pie [Human Resource Violet Trinity]
Rarity [Lead Geologist Valerie Shines]
AppleJack [Major Laborer Alice Trents]
Fluttershy [Fauna investigations Flora Davidson]
RainbowDash [Advanced Chemist Zedella Glores]

Any and all Interviews are halted after Rainbow Dash attempted to infect personnel.