The Blacks: The Last Generation
There are some lost souls that go throughout their entire lives searching for who they are. They waste time in this quest and never find that which is sure to complete them.
Regulus went throughout his life knowing who he was, but failed to complete himself because he let the people around him drag him down to the fate he chose not to fight against. Sirius found himself amazingly early and passionately asserted this to the world, only to break himself from inside when he saw that, after all, he didn't have what he needed.
Bellatrix never had a childhood and never had the pleasure or luxury of innocence. Always broken, always empty, and always lonely. A genius by herself, she plotted her path to security, only to give way to madness when she realized she had been wrong from the first. But she was in far too deep to pull herself out, and the madness softened the pain of knowing the truth.
Andromeda was a good person and had always been righteous. She saw in others what she failed to see in herself and, regarding their condition, she was sure that she was doing, being something right. She did not say a word, only committed an action that her family received as the blackest and most unforgivable of sins. Andromeda lost herself in the process, but fulfilled herself simultaneously. She could not bring herself to regret, in this life or the next.
Narcissa did not believe in destiny, only responsibility, and fulfilled that as she saw fit. Her regrets were many, but in the end she was satisfied with how her life turned out. Never had a more resilient Black existed.