Gundam Wing Episode 16

Noin reaches the Antarctica base with Heero and Trowa. Zechs meets the two, and shows Heero the rebuilt Wing. Heero says he'll thank Zechs by killing him. (such a nice guy) Heero decides to use Heavyarms instead of Wing, because he's not sure he's worthy of fighting in a gundam restored by his enemy.

When the morning comes, Zechs and Heero face off in front of the base HQ. Tallgeese gives Heavyarms a good thrashing but just as it looks that Tallgeese will win, Relena flies into the middle of the battle waving Heero's letter from Mrs. Noventa, saying he has to read it. Heero tells her to go away (as only Heero can,) and Zechs politely asks her to leave and let him seek vengeance for the soldiers he's lost to the gundam, but she doesn't. She orders Zechs to stop fighting in the name of the Peacecrafts and he decides she need a lesson in how terrible war really is. He sets to work beating up Heavyarms, and Relena orders Heero to kill Zechs. (I don't know why she thinks he'll take orders from her, or why she thinks he hasn't been trying to kill Zechs for the past three hours!) Noin steps in from the base HQ and tell Relena not to wish for the death of her own brother, which comes as a shock to Relena, who didn't know at that point that she and Zechs were related. Noin confesses to Relena that she loves Zechs and has to abide by what he wants to do.

The Investigative Committee's troops arrive and Trowa suggests the three gundams each take a third of them, but Zechs insists that the gundam pilots, along with Noin and Relena, get away and leave him to surender to them when everyone has left. As he heads off to fight them (making sure the others get away) he yells, "Glory to the Colonies!"