This’ll be short because I’m still workshopping a lot of lore, essentially:
E.C is an 11 year old that survived thanks to defense from his brother, creature, but during a scavenging trip, he wandered off, got mauled by infecteds, and later was reanimated into mirage E.C.
Mimic Creature is a member of a species of mimic whose only goal is to deceive and kill survivors, including whoever they’re mimicking.