THEME:

 The fault, Dear Brutus, is not in our Stars, But in ourselves that we are underlings means that it is not our fate that makes us underlings, but our Own Weakness. The fault, dear Brutus, is not in our stars, But in ourselves" Peter was saying that the fault is in the nature of things..not in how you do them, or even just in yourself generally. This becomes important because it was "fate s fault" when Augustus died, not Gus' fault. So therefore, the Fault is In Our Stars, and we can do nothing about it. We don't have a choice in the matter. Another meaning could be, people closest to us can be seen as stars. The fault in them is that they burn out, they die! Some go before others, but eventually everyone will be subject to same fate. It's something we all possess and cannot stop. Some circumstances and situations you can't control and the characters were in that boat where they couldn't control what they were facing.