No bones about it, Brook is the only musician that could fill out the position for the Straw Hat Pirates. The jolly skeleton with an afro has a long (LONG) history of both joy and tragedy. So, who is the Straw Hat Musician, and how does Brook become a crucial character in One Piece?
Fair warning, this article contains spoilers up to the current Egghead Island arc. If not caught up, One Piece is available on both Manga Plus and Viz platforms to read. So, read on with caution, or turn back now!
How Old is Brook?

When Brook debuts in the Thriller Bark arc, he’s eighty-eight years old, and ninety after the time skip. Not only does it make him the oldest Straw Hat Pirate, but also the most qualified to run for United States politics! While he may be the oldest Straw Hat, over half of his life was spent drifting alone in the Florian Triangle. That’s likely to impede maturity a bit, and Brook makes every case for it with his behavior. Despite his almost century of life (sort of), Brook has the sensibilities of a thirteen-year-old boy.
Was Brook On Another Crew?

During his first lifetime, Brook was the first mate for the Rumbar Pirates. A cheerful crew from West Blue enjoyed music and partying, and eventually, their music attracts Laboon, a small whale. When Laboon follows them too far and loses his pod, he ends up following the Rumbar Pirates throughout the West Blue and becomes great friends with them. The whale even follows them through Reverse Mountain, where they know he can’t survive the Grand Line with them. They make an agreement with Crocus the lighthouse keeper, who promises to look after Laboon until they return in three years.
Of course, they never return. On the Grand Line, Captain Rumbar falls ill and eventually dies along with a decent amount of the crew. Brook, who ate the Revive-Revive Fruit sometime before, took over as Captain and led the Rumbar Pirates from there. It didn’t last much longer, though, as they soon were lost in the Florian Triangle and starved to death. Brook was the last alive out of them and leads everyone in one final rendition of Binks’ Sake, recorded on a Tone Dial for Laboon.
Is Brook Dead?

Yes… and no. Brook’s Devil Fruit was a mystery to him until he finally died for the first time. During his first life, he assumed it was just useless, taking away his swimming ability for nothing in return. After he dies though, his soul floats around the Grand Line for years before he finally finds his body again. Brook was able to reclaim his body, but it was a bit late and all that was left was bones and hair. So, while Brook is dead in the physical sense, he’s still able to move and communicate as he did when alive. Now he’s just a little more spooky.
How Does Brook Join the Straw Hats?

Unfortunately for Brook, he finds his body still drifting in the Florian Triangle. All he can do is walk his old ship, too broken to do anything but drift along, and make coffins for his old crewmates. Brook grows a little eccentric during his time alone, understandably. He first meets the Straw Hat Pirates when they enter the Florian Triangle. Though he jumps onto the Sunny and introduces himself, he insists he can’t join them until he regains his shadow. Of course, this leads to Brook teaming up with the Straw Hats to take down Gecko Moria. Finally free to see the sun again, he joins as their musician not long after.
Strange as it is, he’s not with the Straw Hats for long before they’re separated at Sabaody Archipelago. Sent to a nation in civil war, landing smack in the middle of a demon-summoning, Brook almost hit the jackpot. Those who summon him obey his every demand, but he’s soon a hostage of their opposing Longarm Tribe. They immediately see Brook as big money.
Soul King Brook

Brook works in a somewhat win-win situation here, able to train and tour the Grand Line at the same time. The skeleton man becomes a musical sensation as the Longarm Tribe exploits him harder than any pop star since Britney Spears. Brook makes international acclaim and returns to the Sabaody Archipelago the same day the Straw Hats reunite. His managers aren’t happy when he announces it’s his final show, but Brook shows off some new abilities to escape.
Does Brook Have Powers?

When he first joins the Straw Hat Pirates, Brook is only a proficient swordsman… sword-skeleton? Either way, he doesn’t truly unlock the powers of his Revive-Revive Frruit until he hones his Soul King music. Now, he holds much more power over his own soul, able to expel it from his body to scout out far areas. Brook has also combined his power with his music, with abilities to lull enemies to sleep through song or even freeze them solid.
Whole Cake Island Arc’s MVP

Brook really comes through for the Straw Hats in Whole Cake Island. While he goes to get the Poneglyphs with Pedro, he does end up caught by Big Mom. Thankfully she recognizes him as the Soul King and has a thing for collecting odd individuals. She ends up cuddling him like a stuffed animal. It’s only thanks to the other Straw Hats’ quick thinking using Brulee’s powers (unwillingly) they get him back. Even though he was kidnapped and held hostage, Brook pulls the Poneglyph etchings from the storage in his skull. Under the greatest pressure, he somehow manages to pull through, bringing Luffy closer to Pirate King.
What is Brook’s Dream?

Brook dreams to finish sailing the Grand Line and reunite with Laboon. He and the other Rumbar Pirates made a promise with the whale over fifty years ago now, and he intends to honor it with the Tone Dial he’s saved. Brook holds onto this promise, and it drives him in every moment that seems hopeless. Not only does he know that Luffy will become King of the Pirates, but knows that Laboon is still waiting for him all thanks to the Straw Hat Captain. Laboon has something to hang on for now too! The news of the Straw Hats’ exploits has spread far, and Crocus shows Laboon Brook’s wanted poster. The whale is happy as can be and knows he’ll see his old friend very soon.
What’s Next ?

Brook got a substantial boost in his bounty after the Wano arc’s climactic battle. He now sits comfortably at 383 million berries, up there with most of the other Straw Hat Pirates (other than Monster Trio). The skeleton is, along with the other Straw Hats, in the upper sphere of Punk Hazard at the moment, but they’re turning the tables. At the end of the last chapter, the pirates were getting ready to make their counter-attack and breakout. Doesn’t hurt that they have the knowledge of Dr. Vegapunk and the strength of Cipher Pol 0 members Rob Lucci and Kaku backing them up.
Brook could be one of the secret weapons the Straw Hats need here. He’s light enough to run on water, which will throw the multiple Navy ships surrounding them off, and he can go on a wrecking spree. If he does anywhere near the damage he causes in Totto Land, the Navy will have a huge problem.
For now, Brook is going to follow his captain’s orders to escape Egghead Island. He’s close to realizing his dream of seeing Laboon again, and he’s not going to let anything stand in his way. Not even a Navy force larger than any Buster Call will stop Brook from reuniting with his best friend once more after half a century away!