These are the reasons why heather didn't get voted off at the bonfire ceremonies she was at:
Dodgebrawl: Noah was lazy and didn't help in the challenge, so they voted him off instead
Not Quite Famous: Heather convinced everyone to vote off Justin
Up the Creek: Izzy made them lose the challenge
Paintball Deer Hunter: Cody wasn't helpful anymore after he got mauled
If You Can't Take the Heat: Beth caused bad luck to the Gophers
No Pain, No Game: Eva was too psychotic, and she had anger management issues
Search and Do Not Destroy: (Heather got invincibility) Leshawna convinced everyone to vote off Trent or Heather after Trent cheated on Gwen
Hide and Be Sneaky: (Heather again got invincibility) The guys voted off Bridgette because she was a threat to the boys
That's off the Chain: (Heather again got invincibility) Lindsay lost the challenge
Hook, Line, and Screamer: DJ ran away screaming without seeing the killer