Firstly a little background. Maul was once a protege of the main negative antagonist in Star Wars... Emperor Palpatine. However, after he lost a battle with Obi Wan Kinobi after an attempted assassination, the emperor moved onto other apprentices, the one he most liked being Darth Vader, so Maul was left hating both of them. Wanting revenge on Obi Wan Kinobi for the loss of his legs and hating the emperor for the same reason everyone does in the film... He's pure evil! This is a scene from Star Wars the Clone Wars where the emperor catches up with Darth Maul, who is attempting to put together an army to gain power for himself:
The animated characters are less true to life. Palpatine is good in this but animated and intelligent like true negative beings are not. Maul, in the whole series is even more so. Occasionally he kills an innocent person for no reason but most of the series, his thinking process is not particularly negative. He displays an animatedness, intelligence and above all, self awareness and honesty that negative beings do not have. He is simply out for his own gain and in his own very tortured way, his own healing. It would not occur to Maul to lecture others on his own moral superiority, he knows he's a bad guy that makes him not a true bad guy... This is the end of his journey:
After Maul is struck, and when he lays their dying, he asks:
Maul: Tell me, is he the chosen one?
Obi Wan: Yes
Maul: He will avenge us.
This is beautiful, because even though Maul has shown absolute unwavering hatred towards Obi Wan, he suddenly acknowledges that him and Obi Wan have a common foe that is the real bad guy, the Emperor. In this, Maul manages to attain a kind of redemption that he has managed without any of the more cheesy mechanisms of the endless conversions to the positive side of the force that characters take in other shows.
It is also a tacit acknowledgement that the torture the emperor put him through is a large part of the reason for his behaviour. In that first clip we see the emperor torturing Maul after he begs for mercy and we don't know what Maul went through before we see him in the episode 1, to make him into Maul.
These are interesting thoughts!