The Line, the title

I was wondering about the title, and thought of crossing the line between good and evil.

Claire played a dirty trick on the other cheerleader after West convinced her that 'by definition, she was better.'

HRG crossed back over the line when he coerced the guy in Odessa intogiving up information, then murdering him.

Mohinder refused to cross the line when he didn't inject Maya.

Maya crossed the line (not just the physical border) when she murdered Americans to sneak into the country.

Hiro crossed the line when he decided he was willing to destroy the spacetime continuum by kissing Yaeko, thus pushing Kensai to the 'dark side', so that he may one day be the one who murders Kaito, and who knows what else.

Peter had a segment too, but I'm not sure what line he crossed, except a journey into the future.

International Date Line maybe?