Shanks is a character that has only appeared a few times in the story despite his role being quite important. We don’t have that much information about his past or his objectives, so I won’t try to theorize things such as whether he is the bad guy of the story or not. However, I believe that, it is still possible to guess the essence of its character.
From Roger To Shanks And From Shanks To Luffy.
If you were to ask yourself, who is Shanks? Well, you could answer that he is one of the strongest pirates in the New World, and the one who gave Luffy its ambition/dream to become the next Pirate King. He was first a young rookie in Roger’s crew, and it seems that there was a special bond between him and its captain, since he received the straw hat from Roger.
Would a parallel between its former connection to Roger and the one he has now to Luffy be relevant to the story? One could think that the same way he gave his ambition to Luffy, he might have received his from Roger (this being symbolized by the Straw Hat being passed down).
What I am trying to theorize here is actually the opposite. I believe this a “two side of the same coin” case there and I am basing everything on the panel below (which is not a solid proof I know, I am just sharing my thoughts, not trying to make a point), so what’s my idea?
My guess is that instead of pushing Shanks to pursue and fulfill his dreams, Rogers actually shattered them. I do not say that Roger was someone disrespecting others dreams, but Shanks dreamt of something that was impossible to realize, and by doing so Roger prevented Shanks from wasting his life pursuing something that was unreachable.
The fact that it occurs after Roger reached Laugh Tale might be relevant too. Imagine Shanks joining Roger’s crew because he is looking for a way to make his dream comes true (there is probably no better way for this than joining the future pirate king).
His rookie years pass and after exploring a large part of Grand Line without having a clue about how fulfilling his dream, he learns about this last island that is still undiscovered and finally feels like what he is looking for, must be on that island.
That would explain why he burst into tears after asking to Roger if he found something on Laugh Tale, because Roger had to tell him the sad truth that there was nothing there that could have helped him.
People’s Dreams Don’t Ever End?
If you are still reading (thanks!), note that this theory echoes directly to Blackbeard’s Ideology. Thus resulting in a confrontation between the man who had to gave up on his dream and the one who believes that someone should always pursue his (Blackbeard and Shanks have already clashed in the past, resulting in Shanks receiving his famous scar).
This would allow Oda to explore another facet of one of the most iconic One Piece’s topic, dreams, either by making Shanks the exception that confirms the rule or by saying that sometimes, it is better to give up on them.
I will conclude this theory by saying that Shanks maybe learned from his own experience and gave Luffy, a dream that even if it is unlikely to be fulfilled, it can still happen. If this theory were to be true, Shanks would become the man that has his dream crushed and yet still managed to inspire others and became one of the four Emperor.
Theory by Dax201 (https://www.reddit.com/user/Dax201)