Whatever else you've got to say about Guy Gardner there is no denying that all he's ever wanted to do is be a Green Lantern. Even back in the bad old post-Crisis days when he tried to kill Hal Jordan it was only because he didn't want any rival to his title as Green Lantern of Earth. After he was stripped of his GL status he sought out the next best thing, Sinestro's yellow ring, because he could not imagine a life without ring-slinging.
Despite his checkered history and a few too many bumps on the head, Guy has come to epitomise the very best that a GL can be. He is prepared to roll up his sleeves and get down and dirty for the Corps. He'll take on the missions that no-one else would consider and get the job done. He'll defy Guardian edict without a second thought if he holds his actions to be in the best interests of his brothers and sisters-in-arms. You can be sure he'll be on the front line in every conflict standing shoulder to shoulder with his fellow lanterns. He'll be the one to provide covering fire while other GLs are getting the hell out of there.
It is ironic then that Guy's greatest moment as Lantern came at a time when he was not even sporting a green ring. He was in fact wearing two different power rings and neither was green. During the 'War of the Green Lanterns' when the rogue Guardian Krona restored Parallax, the yellow impurity, to his long-time home in the Central Power Battery on Oa so that he could use the fear entity to corrupt and control the Corps for his own nefarious purpose. Guy and the Earth GLs had escaped his clutches and, finding their own rings useless in the face of Parallax's manipulations, had donned rings from the other Corps of the emotional spectrum. Guy was not particularly happy at having been allotted rings representing opposite ends of the spectrum, red for rage and violet for love.
It was only through harnessing the energy of these extreme opposing forces that our heroes could eject Parallax from the battery and restore the Corps' to full cognisance. To do this Guy has to confront his own fractured psyche but laying bare his innermost feelings, even to himself, does not come easy for a space-cop who thrives on machismo. The raw emotion leaps from the page as the Green Lantern admits his greatest love and his ultimate rage are inextricably linked - his love, his life, is the Corps and the idea of that life being denied to him fuels his burning anger. In that moment Guy does what no other Lantern could. He smashes through the Power Battery and rips Parallax from its depths.