Dreams are important.

Elsewhere, Chopper knows that this concept is seen as a fanciful, childish thing, but on the Thousand Sunny, it isn't so much of an idea as it is fact. Luffy likes meat, Nami likes money, Brook makes skull jokes, Zoro will always manage to bleed more than everyone else and dreams are important. End of story. But at the same time, he worries and frets and doubts, not because the others' dreams seemed far off, but because of his own.

As far as Chopper is concerned, the rest of the crew's dreams are halfway to completion. Usopp is a braver warrior than he believes, Luffy will become the Pirate King, which means Zoro will become the greatest swordsman in the world, and Sanji wouldn't allow that to happen unless he found All Blue first. By the time they got to All Blue, Nami will have mapped the world, and Robin will definitely find what she's looking for. Then Brook will find Laboon, and Franky's creation would make it to the end of the world. Those would happen. It was inevitable.

His dream looks more and more unattainable every day. To cure every illness? In a crew where half of them can't even get sick? It's impossible, he thinks, but it's more than that. To cure every illness in the world means to find every illness in the world, illnesses that aren't described in his medical books, illnesses that Doctorine hadn't shown him. What if one of his crewmates fell ill, and after poring through textbook after textbook, he still had no idea what to do?

He cannot let that happen.

Oh, he's a good doctor. A damn good one. Even he's able to admit that to himself on occasion, after a particularly vicious bout with an enemy, scuttling back and forth from patient to patient and watching the gratifying process of wounds healing over. He is the only doctor in the world able to see how bones heal themselves naturally without messy flesh and blood getting in his way, and there's nobody quite like him for really tiny stitching where metal and flesh meet. And that's not even taking Zoro into account, who's both a medical mystery and a medical marvel in one. No, he's good at that, and he's good at healing drastic wounds, and he's good at healing fast because there's no room for mistakes in his line of work, but those aren't illnesses. Illnesses are terrible, insidious things that many don't notice till they're too late, things that can't be healed by suturing and stitching and painkillers and lying down for a month.

It's these thoughts that lead him to lock himself in the sick bay, taking great care to ignore the sounds of mirth from on deck. Some days, he had to concentrate. He had to, if he wanted to memorize every disease so he could be prepare and be ready for when the inevitable came. For a moment, he wishes for Robin's willpower to read book after book without getting tired or even bored, wishes for her skill to soak up all she reads like a sponge.

"Oi, Chopper! What are you still doing down there?" That's Usopp's voice, echoing down.

"I'm busy!" He calls back, even as he feels his willpower wither. It always does, in the face of Usopp and Luffy.

"But we need a third person!" Luffy yells, and there's a small scuffling sound which, Chopper thinks, probably means his friends have been wrestling.

"If he's busy, he's busy," says Usopp's voice, " Go bother Zoro. And don't tell him I said that."

Chopper breathes a sigh of relief and sits back in his chair, idly swiveling to and fro. There's not much to be said for peace on this ship, but this is his area, and Franky had sound proofed it the best he could. Of course, it doesn't quite muffle Luffy and Usopp's screeching or Sanji and Zoro's fighting, but it does a pretty good job. Still, he has good enough hearing to hear a third voice up on deck.

"Chopper is still busy? I believe I shall pay him a visit."

The distinct tapping sound of a cane and the scent of tea betrays Brook's arrival before the skeleton himself pokes his head into the room, much to Chopper's chagrin. Brook is good company most of the time, but he appears to have the insatiable need to be constantly moving, constantly active – and after years stranded, he can hardly blame him. Still, this is not the company he needs. He needs to study.

"You're not hurt or anything, are you, Brook?"

Brook takes a seat upon the bed reserved for patients, long legs folding up to his chest in a way faintly reminiscent of spiders. "Not to worry. I am not sick in the slightest—save for being dead, of course!"

Chopper waves away the ensuing mad laughter, but is elicited to look up when Brook speaks again in a far more genuine tone. "I simply came to check up on you. As I recall, you had finished replenishing your stocks and treating the crew, correct?"

"I'm just going through my books."

"I see."

They sit in complete silence, punctuated by the crackling of the turning of pages. Chopper wonders what Doctorine would say about Brook, how she would treat him. Scanning through the pictures of swelled glands, vicious viruses, wounds unable to close, he remembers a few of his first patients, people who would have survived if they had been brought over more quickly. A girl of seven, lost to pneumonia. A young mother. An old man. That's who it always was, he remembers, and even with the correct ingredients, well… it's as he remembers Doctorine saying, gently pulling blankets over the newly deceased. You can't save them all. But you can save some. And the unspoken, So it's worth it, in the end.

But with Brook, silence never lasts for long. Chopper's reverie is suddenly dispelled with the invasive sound of bone against metal, an insatiable rhythm spouting from Brook's fingers, soon to be accompanied by his own humming. The way he's seated, fully erect, makes him look like a vibrating toothpick, Chopper notices, until he stills himself to speak. "Your dream is to be able to cure every disease, correct?"

"A-ah… well, yeah, it is. How did you know that?"

"Usopp told me."

Which is unlike Usopp, Chopper knows. As much as he enjoys weaving his tales, he never talks about his crewmates' pasts. It's just something you don't do. But there has to be a reason for that, right? The silence this time is not comfortable, but ringed with the slightest bit of tension. The reason for that, Chopper notices, is the absence of sound from the musician—he is sitting completely still.

And then he speaks, quietly. "There are many diseases on the Grand Line. Many, many different ones from everywhere else." Ones you can't read about. Ones you can't cure.

Chopper nods. "I know."

"My Captain, Yorki died from one."

At this admission, Chopper's heart falls into his stomach. He knows about Brook's past, of course, but there's something about hearing a name. Then Brook shrugs, and such a simple movement says far more than his laughter ever can. It says that people die. It says that life goes on.

Brook continues. "But we were never very focused on doctors, so I do not know if it could have been stopped. We only cared for music." He chuckles to himself. "But learning to cure all diseases is a good dream." Suddenly, Chopper understands why Usopp would tell Brook such a thing.

He takes a thermos from out of the insides of one of his massive suit pockets, and takes a small sip of tea from it. "I am no doctor, but I have seen many diseases. Perhaps I can tell you about some. Would you like that?"

Chopper closes his book, and swallows. "Yeah," he says, then goes on with a bit more enthusiasm. "Yeah, I would!"

"Then I shall start straightaway! Yohoho! How splendid!" And just like that, the somber mood is gone, replaced by Brook's usual exuberance.

They spend a long time talking about diseases, and notebooks quickly fill up, but Chopper's happy for reasons other than purely academic ones.

They've all lost people along the way, but they will be remembered and documented in books for much longer than any regular lifespan. And as a wise man had once said to him, so long as a man is remembered, he is alive.