Hint 1:
The fires are heavily related to connection.
Hint 2:
There is something about the fires you will never see.
Hint 3:
They are somewhat similar to the flowers (introduced in Inclusive.)
Hint 4:
What would happen in the moves that it blocks you from making?
Answer:
Fires cannot be disconnected. If a move would end up with them being disconnected, the move is blocked and the turn is cancelled. You will never find a disconnected fire.