I was getting ready to call the "Petrie Prompt," because there was just so much Petrie in here. Petrie this, and Petrie that! Petrie, Petrie, PETRIE! 
I suppose that a prompt like "belief" tended to fit some with low self-esteem like Petrie more?

Everyone did a fantastic job (once again, prompt probably lended to that). After mulling over it, I have to go with Sovereign's
One Fallen, Two Torn Apart. Apart from actually characterizing Petrie's father, the entire piece (srsly 20K words
how) felt like a legitimately prologue of Petrie's family to the entire LBT film series as a whole.
How Pterano's and Volant's relationship wind up strained and changed from what they were to how they ended up by
Stone of Cold Fire is the star of this story. Pterano slowly lets his bystander syndrome during his sister's mate death and his guilt turn him into being a more outspoken, egotistical leader to make up for it, and their final argument and separation after apparently losing Petrie as well ended on a dramatic note.
Though it's interspersed with nice familial bonding moments, the melodramatic (it
is Pterano) emotions and the souring relationship between the two siblings as time slowly passed just spoke to me. And in a sense, they both believe in themselves and their own separate ways by the end. By the end, I really felt like the catalyst of their crumbling relationship was that one fated death at the start, and while their beliefs have shattered from their original ones before it all started (ie. 'let's be a wonderful family' was what I felt), their new ones are... bittersweet.