Disclaimer: I do not own Gavroche or anything Les Miserables, including the song.
Gavroche could hear them talking just as well as anyone. And he was small enough to slip between musket barrels and legs to get close to Enjolras and Marius without them noticing. So he could hear what they were saying. And he did not like it.
Gavroche had more hope in him than all the men on the barricade put together. They were realistic—they knew that they were going to die. But Gavroche was ten years old. And ten-year-olds never think that they are going to die.
It was because of this hope—this obstinacy—that Gavroche knew he could help. He wasn't big enough to fire a musket, and he wasn't old enough to kill a man, but he could reload. It was through his time spent reloading muskets that he knew ammunition was running low. When he overheard Enjolras tell Marius that if they didn't find more cartridges they might as well give up now, Gavroche's suspicions were confirmed. It was when Marius and the new volunteer—Jean Valjean—started arguing over who was to risk going outside the barricade to find ammunition that Gavroche realised what he had to do.
"I'm going!" he shouted, leaping up onto the barricade. He caught up one of the sacks that had not yet been torn up for bandages and climbed higher, to a tiny hole he knew only he would fit through.
"I'll be right back!" he called, flashing a smile back at the pale, worried faces below him. Telling them not to worry and that he was the only one little enough to get away with the job unseen would have made no impact on them, so he half-ignored their protests as he quietly climbed down the outside of the barricade.
"Gavroche, get back!" Enjolras called, his voice quiet but carrying. "It's too dangerous!"
"What do you think you're doing?" Marius asked, his voice rising half a pitch with worry. "What are you thinking?"
"He's going to get shot," one voice whispered.
"The fog's thick. He'll be fine."
"But what if—"
"Quiet." Valjean's voice was quiet but firm and the others stopped talking. "Gavroche, stay as low as you can." The boy immediately crouched as he padded slowly along the base of the barricade.
"Run as quietly as you can to the first soldier. Stay behind the body!" That was Enjolras. Gavroche did as he was told, only half listening to the whispered calls of encouragement and warning from the other men inside.
The first man he crouched over was middle-aged and fat, stuffed into his uniform, his buttons about to pop, with a wine flask at his belt. Gavroche wondered how he had made it into the army at all. He collected the soldier's cartridges and emptied his pockets of ammunition. His first cache rustled softly in his sack as he ran to the next body.
Gavroche's obstinate hope kept him crouching behind the dead men as he packed up their ammunition, kept him running quietly and bent double to the next man. But there grew a little, nagging doubt in his mind when the fog began to clear. There was a light winking in the distance, and he hoped against hope that it was not the National Guard, though who else it would be, he did not know. He heard a groan from behind the barricade and Enjolras' whispered warning.
"Only two more," Gavroche murmured back—but time was running out. As he ran to the second to last man, his footsteps echoed softly, no longer dampened by the fog, and he thought he heard a musket cock. He prayed to the goddess of his lasting luck that it was just his imagination, but—
He dived behind the dead soldier as a musket ball hurtled past the place he had been a moment ago.
The men behind the barricade were shouting now. The enemy had seen their little hero, and there was no longer any need for secrecy. But whether Gavroche could not hear their cries or if he was just ignoring them, he did not heed them. They pleaded with him to come back, told him he had enough ammunition, reminded him of the terrible danger. But it was to no avail. Gavroche would finish the job, even if all his luck ran out.
This second to last man whose pockets he was emptying now was young and handsome. His face reminded Gavroche of the look that haunted Enjolras' face, and Marius'—determined. He felt his courage waning. He did not look back at the barricade yet, knowing it would cause him to lose all his strength and run back inside, where it was safe—or, at least, safer. He had but one man left, and his luck had held until now. Perhaps he would tease out two more minutes of Lady Luck's time…
And little people know
When little people fight
We may look easy pickings, but we've got some bite…
It was part of a little song that he had heard somewhere a long time ago and sung earlier that evening. Gavroche had always thought it described him and his fellow "little people" of the streets almost perfectly. It was something they always hummed in the face of danger. Now, with his strength and courage failing and his unwavering hope wavering, the little song lent him some bravery. He moved to the last man, dodging a few scattered bullets as he went, relief flooding him every time one missed its mark.
So never kick the dog
Because he's just a pup
We'll fight like twenty armies and we won't give up…
Gavroche's breath was coming in short gasps, but his voice was strong, betraying some underlying hope he had never used before. He tied his bulging, little sack shut and ran back to the barricade. His footsteps were very small in the night, and the men behind the barricade held their breath in anticipation, worry, and love for the bravest, littlest one of them all.
So you better run for cover…
He was on the barricade, standing in the little hole. Marius caught the sack full of cartridges as Gavroche tossed it down.
…when the pup grows—
This shot seemed louder than all the rest put together. The song stopped suddenly, and Gavroche fell forward into Enjolras' waiting arms. There was a cry of anguish from the leader of the rebellion and there were tears streaming down his face. He wasn't the only one.
Gavroche's eyes were dark and lifeless, their usual sparkle of mischief gone. His luck—the same that had clung to him through the dark streets of the underworld of Paris and brought him safely out the other side—had deserted him. There was no more courage to be drawn from the little body, and no more hope to spring from his smile. And no matter how many times they called his name, he would no longer answer.
Each bullet they shot from that moment on was shot for him. Each song they sung was sung in the hope that they might draw the same strength he had. They felt that the courage they had did him no justice, and they tried to no longer be afraid. He was their bravest, their most hopeful, their most loved. He was the epitome of what they strove to protect, and they lived for him.
Perhaps, when they died, they heard a strain of a familiar song that helped them to be brave. Perhaps they saw a smile and a pair of twinkling eyes and they grew strong. Perhaps they followed him to wherever he had gone before them—to the place of heroes. And perhaps they lived again.
Little people know
When little people fight
We may look easy pickings, but we've got some bite
So never kick the dog
Because he's just a pup
We'll fight like twenty armies and we won't give up
So you better run for cover when the pup grows up.