It wasn't until DOA4/5 that Helena got all boring with the "I have to act all dutiful" routine or whatever.
Well, to be fair, as some mentions, she had been through a lot.
She was born rich, never taught much about the schemes of her father and underground connections. Got her parents devoured by that same powerplay politics, even her on the line innocent mother was victim. She then went through a dark period with no allies, and found no responsibility for her current station, as she focused more on an urge for revenge. However, she managed to turns things around and tries to make everything right, leaving selfish reasons behind. She was even prepared to become a martyr for it, as she didn't expect either understanding or aid (Hello Dark Knight Batman).
However, she was saved at the end of her time, and her heroism advanced and confirmed her personality. She was no longer the spoilsport child, unfit to be king, or in the phase of shock with the mental instability and paranoia. She had moved past that and earned her spot as a suitable leader. She was now worthy, and assumed the position. From there she had both turned a new leaf for herself and the organization.
It just makes sense you know.