Least Is First

"I will take the Ring, though I do not know the way."

—Frodo, The Lord of the Rings

The Hero needs help and is urging a dangerous plan on a reluctant group of people. Who's the first to say he'll join in? Why the youngest (or most seriously aged), the least experienced, the most unskilled, the weakest member of the group. Often results in many, if not all, of the other characters being shamed into joining.

If the character's inexperience and youth are such that he doesn't know what he's getting into, Silly Rabbit, Idealism Is for Kids may come into play. It may still shame them.

On the other hand, the character can know. This is even more shaming.

This character may find the actual conflict very hard but will stick to The Hero until the bitter end.

Contrast Sour Supporter, Who Will Bell the Cat?.

Examples of Least Is First include:

Literature

In One Flew Over the Cuckoo's Nest, Charles Cheswick is the only man who is initially enthusiastic for McMurphy's scheme to change the ward schedule.
In Terry Pratchett's Night Watch, when Vimes asks for volunteers to stay, his past self is among the first. Vimes finds it too eager, even.
In Graham McNeill's Warhammer 40,000 Ultramarines novel Dead Sky Black Sun, when Uriel appeals to a group of Space Marines and two Imperial Guardsmen to help him, it is the Guardsmen who volunteer first. And when one dies, and the Marines decide to leave, the surviving Guardsman assures them that he will go with them.
Frodo at the Council, in JRR Tolkien's The Lord of the Rings
- The book does this trope twice. First Bilbo (who's aged and in no condition to undertake such a journey - thus weaker than Frodo) offers to take the ring - since he figures he started the whole thing. Gandalf praises him but remarks he's being silly - Sauron is the one that started all this, no one can hold Bilbo accountable. As they can't reach a decision (and inspired by Bilbo), Frodo offers to take it, which prompts the rest of the Fellowship to form when Sam says he will not be going alone.
In CS Lewis's Prince Caspian, when Lucy insists on following Aslan when only she can see him, Edmund is the first to say he will go with her.
- But he'd learned his lesson in the previous book, The Lion, the Witch and the Wardrobe, where he was very reluctant to go with the others.
A slightly different take on this scene happens during a siege in the second book from A Song of Ice and Fire. The besieged forces draw back inside the defenses at one point out of fear of wildfire, (a magically enhanced, virtually undousable flame) that their own side has used to set the battlefield ablaze. This lets the forces attacking them get right up to the gates and start trying to batter them down. The soldiers, even the Badass Blood Knight leading them, (who, by the way, got half his face burned off as a kid) refuse to go back and fight. At this point Tyrion, who is a dwarf, (not a fantasy dwarf, but a human who happens to be about 4 feet tall) rides up and tries to get the soldiers to go back into the fight. They refuse. Tyrion then goes to lead the attack himself, shouting at the tough guy soldiers "They say I'm half a man. What does that make the lot of you?" True to form, that shames enough of them into fighting that they make a difference in the tide of battle.

Film

The movie Hook has a particularly saccharine (though aren't they all?) example: the lost boys have a new leader and are unwilling to recognize the adult Peter Pan as their erstwhile friend until the littlest hesitantly walks over, touching his face and looking into his eyes, until the kid sees Peter in him, and then everybody rushes over to see for themselves.
In The Movie of The Return of the King the first one to charge at the armies of Sauron at the gates of Mordor is Aragorn, actually, but Merry and Pippin are the first to follow him.

Live-Action TV

In the Doctor Who serial The Sun Makers, the outlaw Others are unwilling to help Leela rescue the Doctor. It's the just escaped worker who offers. The Others do not follow until later, when the Doctor returns to rally them.

Tabletop Games

Dungeons & Dragons module OA5 Mad Monkey vs. the Dragon Claw. If the players have their PC's refuse to undertake the adventure, the aged and weak owner of the inn they're staying at volunteers to do so.

Video Games

Statistically Speaking, this is incredibly common in video games, especially RPGs. People who join the hero early will generally always have low levels and basic equipment (and if they don't, don't expect them to stay in play for long.) May lead to Overrated and Underleveled.

Western Animation

Occurs in Star Wars: Clone Wars: When Anakin returns with the horribly mutated males of the local Proud Warrior Race Guy tribe, a small child is the first one to welcome them back to the tribe.
In South Park, Cartman delivers a rousing speech in an attempt to persuade people to address the menace of Scott Tenorman. He succeeds only in enlisting the wheelchair-bound, mentally retarded Timmy.
- And then Timmy changes his mind.
  - Of course, Cartman didn't need their willing help anyway.
At the end of Disney's The Hunchback of Notre Dame, Esmerelda leads Quasimodo out of the church before the waiting citizenry. After a hushed pause, the first to embrace/accept Quasi is a small child.
Ducky in The Land Before Time is the first to snap Littlefoot out of his funk.