'We know the Ring is no laughing-matter; but we are going to do our best to help you against the Enemy,' says Merry to Frodo at Crickhollow (FR 1.v.104), revealing for the first time the stout heart and shrewd mind he shows throughout the tale. There are, however, a couple of moments involving the Ring and humor that are themselves quite telling about the characters involved.
In The Prancing Pony, Strider several times indulges in humor at his own expense as he tries to convince the hobbits that he is not only a friend, but also the genuine Strider. He banters with Frodo about his 'rascally look', 'with a curl of his lip and a queer gleam in his eye' (FR 1.x.164). He takes up Pippin's glib comments about 'lying for days in ... ditches' making them all look like Strider and responds that they would die in those ditches years before they looked like him, 'unless you are made of sterner stuff than you look to be' (FR 1.x.170-71). Later he jokes with Frodo about how he looks: '"I see," laughed Strider. "I look foul and feel fair. Is that it?"' (FR 1.x.171). (Note also how Tolkien uses the easily spotted allusions to Shakespeare in these last two statements to draw our attention.)
But even before this last jest Strider's grim and self-effacing humor has already culminated in his pretending to threaten them to kill them and take the Ring, all in the effort to make a point to them about who he is, and is not:
Pippin subsided; but Sam was not daunted, and he still eyed Strider dubiously. 'How do we know you are the Strider that Gandalf speaks about?' he demanded. 'You never mentioned Gandalf, till this letter came out. You might be a play-acting spy, for all I can see, trying to get us to go with you. You might have done in the real Strider and took his clothes. What have you to say to that?'
'That you are a stout fellow,' answered Strider; 'but I am afraid my only answer to you, Sam Gamgee, is this. If I had killed the real Strider, I could kill you. And I should have killed you already without so much talk. If I was after the Ring, I could have it – NOW!'
He stood up, and seemed suddenly to grow taller. In his eyes gleamed a light, keen and commanding. Throwing back his cloak, he laid his hand on the hilt of a sword that had hung concealed by his side. They did not dare to move. Sam sat wide-mouthed staring at him dumbly.
'But I am the real Strider, fortunately,' he said, looking down at them with his face softened by a sudden smile. 'I am Aragorn son of Arathorn; and if by life or death I can save you, I will.'
Turning from one Captain of the Rangers to another, we find a similar moment with Sam and Faramir in Ithilien. In his righteous eagerness to defend Frodo from what he feels are the unjust insinuations of Faramir, Sam gives away the secrets his master has tried so hard to conceal, that it is the One Ring which Frodo is carrying, and that Boromir tried to take it from him.
'Now look here, sir!' He turned, facing up to Faramir with all the courage that he could muster. 'Don't you go taking advantage of my master because his servant's no better than a fool. You've spoken very handsome all along, put me off my guard, talking of Elves and all. But handsome is as handsome does we say. Now's a chance to show your quality.'
'So it seems,' said Faramir, slowly and very softly, with a strange smile. 'So that is the answer to all the riddles! The One Ring that was thought to have perished from the world. And Boromir tried to take it by force? And you escaped? And ran all the way – to me! And here in the wild I have you: two halflings, and a host of men at my call, and the Ring of Rings. A pretty stroke of fortune! A chance for Faramir, Captain of Gondor, to show his quality! Ha!' He stood up, very tall and stern, his grey eyes glinting.
Frodo and Sam sprang from their stools and set themselves side by side with their backs to the wall, fumbling for their sword-hilts. There was a silence. All the men in the cave stopped talking and looked towards them in wonder. But Faramir sat down again in his chair and began to laugh quietly, and then suddenly became grave again.
'Alas for Boromir! It was too sore a trial!' he said.
Aside from the simple physical parallelism of Sam Undaunted standing up to a Man literally twice his size, we have him challenging Faramir to prove his quality, just as he had challenged Strider to prove his (though not in so many words). But the parallel works both ways, Faramir responds with humor and a feigned threat, just as Aragorn had done. He stands tall. There is a light in his eyes, and his stern manner frightens them. His 'Ha!' nicely punctuates his statement, just as Strider's 'NOW!' does his. And as Aragorn had suddenly smiled at them to reveal his jest, Faramir does the same with laughter. But their humor offers no simple release. There's too much pain and irony in it for that. Aragorn is the heir of Isildur, who did not destroy the Ring, and he lays his hand on the hilt of the broken sword with which Isildur cut it from Sauron's. Faramir realizes he had guessed the meaning of his and Boromir's dream aright after all -- 'So that is the answer to all the riddles' (emphasis mine) -- and that he was now presented with the same 'trial' as his brother had been, and with a far greater advantage of strength over Frodo than Boromir had boasted of. In the words 'Alas for Boromir!' his own situation confronts him.
Yet both Faramir and Aragorn turn from their sad humor to matters more serious. Aragorn pledges his life to Frodo and the hobbits. Faramir briefly mourns his brother's 'too sore a trial,' and then tells the hobbits that he would not pick up the Ring if he found it in the road, converting a boast he had made in ignorance into a vow he would die to keep. Since both Aragorn and Faramir have the hobbits at their mercy, and the Ring within their grasp, we should not be surprised to recall here another Captain of the Dúnedain, Boromir. For during the scene in Ithilien with Faramir, only the reader is aware, poignantly so, that Boromir did not fall entirely, but after Frodo's escape recognized what he had done, repented of it, and in dying to protect Merry and Pippin redeemed himself. 'Few have gained such a victory,' Aragorn tells him before he dies (TT 3.i.414).
Yet back at the Council of Elrond, when Boromir first saw the Ring and he was pondering the 'riddle' of the dream he shared with his brother, his 'eyes glinted as he gazed at the golden thing’ (FR 2.ii.247). Unlike Faramir and Aragorn, however, he finds nothing to laugh at in the situation or in himself. Boromir came to Imladris to seek 'the meaning of a riddle' (FR 2.ii.247), but the answers he receives offer him nothing but doubt and perplexity. It is only in his 'too sore a trial' that he will find the crucible of his quality.