Outright thievery
Check out Rising Stars a comic that had many heroes and a story about their live in a real world.
Heroes has taking more from that comic than X-men.
For example Nikkie is copied completely from one of the characters in that comic.
I don't think its only one comic they stolen ideas but from many comics cause people like Loeb has worked on and know alot of the people that wrote the comics they have stolen.
Stolen i say cause most comics like Heroes about superheroes in a real world try to come up with new ideas cause they cant steal from people in the same bizz. The creators of this tv show prolly gave money for the ideas. For example Marvel would get angry for using some of their characters. Like Monica being a total copy of Marvel"s Echo character.