If you are searching for a series that is a perfect blend of action, adventure and comedy then you have to watch one piece. One Piece is one of the greatest Japanese manga series of this decade. If you are plan on getting into a long series, you won’t ever be bored with One piece, I can surely assure you this.
One-piece refers to the name given to a world treasure found by the pirate kings Gol D. Roger. This is a mysterious treasure that once belonged to Joy boy during the Vod century. The treasure is said to be of tremendous value, which is currently located in Grand Line, Laugh Tale.
Who is Franky in One Piece?

Cutty Falm, who is better known for his nickname Franky, is one of the main characters of One Piece. He is the shipwright of his pirate group known as Straw Hat Pirates. He is a 36-year-old cyborg. Franky is introduced in the manga as the leader of the Franky Family.
He was originally named Cutty Falm but he never used this name as per the request of Iceburg to hide his identity. In the manga, Franky and his followers were originally introduced as the antagonist of the water 7 arc which was against Straw Hat Pirates until the circumstances forced them to become allies.
We see in the manga that at the request of the Franky Family, Franky was allowed to join the Straw Hat Pirates to fulfil his dream of shipping and circumventing the world. He was the eighth member to join Straw Hat Crew and the seventh to join Luffy’s crew.
Relation between Franky and Brook

As shown in the manga Franky is at first very much annoyed by Brook's skull jokes. He often threatened Brook that he'd shoot him as well as beat him up at the Thriller Bark while Brook continued his jokes. He soon questioned Brook about his past and grew fond of him as he learnt of Brook's hardships. Franky even started to respect the guy.

We also see Franky went with Zoro after Ryuma to get Brooks' shadow back. Also after the war with Gecko Moria ended, Franky along with Usopp by his side made a memorial grave for Rumber Pirates. After seeing this Brook was deeply moved and very emotional. After some time of Brook’s entry into the crew, we see that they both go along very well.
What was the last question that Franky asked Brook?
In chapter 459 of the manga the crew members' shadows were taken by the zombies and only Zoro was left. They were trying to find the weakness of the zombies left there so that they could kill them. Luffy commends the crew for finding the weakness.
Franky even thanked Brook as because of him they all were able to look at their crewmates without shadows. We see that Franky ends up asking Brook, what was the promise he made to the crew that was so important.
Brooks explained that a long time ago his crew left one of the crewmates behind at a certain place, and promised to return. Their crew was annihilated at sea, and so as to not break the promise, Brook remained on that ship for over 50 years when all the members of the crew died. In reply, Franky said that he wasn't even born then and that the person couldn’t have waited so long.
Brook also explains that he is well aware of this fact and even that crewmate, Lamboon had every right to leave. Brook said that Lamboon did believe that a day would surely come when all the members would return back and sing a song for him.
Brook also doesn't believe that Lamboon would forgive them for dying irresponsibly. And if he could, he would scream out to all of them “ Death isn’t an apology”. Franky and Robin were deeply moved by Brook’s sentiments.