Deep down, Fabio...(Spoilers)
Seemed like a good guy. While he is definitely corrupt in both films, he still has goodness inside of him and by analyzing his character you realize is the only way he can survive in this business, by being corrupt. Fabio, in both films, only adapts to his environment of corruption.
A redeeming quality about him is that he never murdered anyone in both films who didn't deserve it and never had a cutthroat and conniving nature to him as the rest of the commanding officers around him had. In Part 1, he was clearly afraid to get killed by his superiors and was the reason why he went into the BOPE training camp after Mathias and Neto save his life, although he got treated like *beep* by Nascimento because of his corrupt nature. In part 2, still grateful to Andre Matias for saving his neck 13 years before, he shows appreciation for him and tries to keep him from getting killed by Rocha for as long as he can, but unfortunately fails after the Tanque raid. However, he shows proper grief upon his death/murder and even sort of "avenges" his death by killing Rocha, whom he hated anyway, at the end of the movie, perhaps because of orders given by the top bosses when they all get exposed by Nascimento and Fortunato gets sent to prison. What do you guys think?