Nobody except Benn Beckmann, and later the rest of the crew of the Red Haired Pirates, noticed it for a long time. Oh, it could be argued that Roger and the remnants of his crew either knew or suspected, but they weren’t telling anyone.
Even Buggy, with his animosity with Shanks, spoke not a single word about it until after it became common knowledge. At least the Clown could say that in this he knew more and was greater than Shanks at.
Benn knew, of course, from the way Shanks would talk about his sparring partner and ‘rival’, and the way he would gush about the scars he had been given. It wasn’t his captains feelings that surprised him.
It was the fact that Shanks didn’t recognize his feelings for what they were. Actually, it was more than that.
There were certain needs that his captain didn’t meet, didn’t even know about if the cluelessness about what some of the crew got up to during shore leave. Benn had thought it impossible for someone not to know, because it was a biological imperative, but… If no one explains it to someone, would they figure it out?
Because he knew his captains history nearly as well as is own. Knew that he’d lost his crew and guardian figures very young, had set out by himself unlike Buggy, and that for the last couple of years before this loss the crew might very well have been too busy trying to reach Raftel to actually sit down the cabin boys and tell them about the Birds and the Bees.
“And,” Benn thought wryly to himself, while pondering these topics during his shift at watch, “Even now Shanks pretty much tunes it out whenever one of the crew tries to tell him. Or gets interrupted by some weird coincidence.”
So perhaps it was just not meant to be for his captain. Benn could accept that… Were it not for the fact that his captain was so clearly in love. Or crushing badly. Or something.
Now, Benn Beckman understood that not all relationships were built on the physical aspect, or even had to include it. And that was all very well and good, but his captain had also seemed to skip over romantic relationships in his childhood. And thus, regardless of feelings-that he didn’t even really understand- Shanks was incapable of just ASKING HER OUT ALREADY!
But years went by, his captain remained clueless, and she seemed to have also skipped something in her childhood because that women, for all that she cared about Shanks just as much seemed as clueless as he.
One day, Benn Beckman vowed silently as they headed to Raijin island again, he would figure out how to pound it into Red Haired Shanks that romantic relationships were an actual thing, and then make sure that he and Dracule Mihawk, the World’s Greatest Swordsman*, both understood that yes, they should totally date. Or get married. Or something other than pine and flirt without even seeming to know what either of those words meant.
The Red Haired Pirates as a whole didn’t really understand the extent of their captains obliviousness until one particular day in the East Blue, on one of their ‘vacations’. It was on that day that they found another former member of the Roger Pirates, one who was pretending to be a weak East Blue pirate(by… actually being a weak East Blue pirate?).
Buggy the Clown was a very interesting person, and while at first it seemed like he hated Shanks and their Captain was being obtuse about it, he actually did care for their Captain. But they noticed something weird while visiting the Clown.
Only Benn Beckman, out of all the Red Haired Pirates, had really believed that their Captain didn’t know anything about romance. The rest just thought that Shanks was either messing with them, or that he was just a bit oblivious. And it did make sense, because Shanks needed Benn to actually keep track of current events that didn’t involve the things he focused on(Mostly Mihawk and the Warlord system. But mostly Mihawk.).
One night, however, after pretty much getting really drunk and sitting around on the decks of both the Red Force and Buggy’s ship, Shanks just kind of wandered off with barely a word. Now, this wasn’t so unusual, because the usually distracted Captain got even more distracted when drunk, and was liable to wander off at the slightest provocation.
No, it was after one of Buggy’s men cracked a crude joke that things got interesting.
“Shanks? He doesn’t know anything about the ‘Birds and the Bees’, or romance in general for that matter,” Buggy explained in almost a mocking tone of voice(though everyone could hear the underlying pity in his tone).
“How could he not?” Cabaji, one of Buggy’s crew asked, “He’s an adult, you don’t get to be that old without figuring a few things out.” But every member of the Red Haired Pirates looked around with dawning understanding.
“You know why Shanks doesn’t know anything about romance,” Benn narrowed his eyes dangerously, “If you tell me, I’ll tell you something that will give you a laugh about my Captain.”
“Deal,” Buggy said quickly not wanting to get on the bad side of the very dangerous man.
“It’s Rayleigh’s fault. I mean, it’s also kind of Captain Roger’s fault through inaction, but mostly it’s Rayleigh’s fault. We were young, impressionable cabin boys, and the person pretty much in charge of our education was Rayleigh. And he thought it was hilarious not to tell us anything about puberty, because it would be funny to make us ask embarrassing questions, except Shanks never did. He just took it all in stride because no one talked about it, and by the time anyone would have realized the crew had already been disbanded and Captain Roger executed,” Buggy gibbered out in a terrified fashion. Because WOW, Shanks had picked a scary first mate.
Benn Beckman seemed to look of into the distance(though a particularly discerning person could tell that he was looking in the direction of Sabaody), “I see. I suppose that next time I see Rayleigh I’ll have to make him understand exactly what he did that was wrong…”
Buggy looked at him flatly, joined by pretty much everyone else, “You aren’t strong enough to match Rayleigh. Like, I know it’s bad, but pretty much only Roger could overpower and outstubborn him and most of the time they were on the same page.”
Benn smiled grimly, “You want to bet? After the torture he has put me through, I’m sure I can think of something. And I think the information I’m about to tell you would be a pretty good punishment for him as well.”
“Shanks likes Mihawk.”
Pretty much everyone erupted in pandemonium before Buggy screamed over everyone, body parts separating, “WHAAAAT? THE WORLD’S GREATEST SWORDSMAN, DRACULE MIHAWK!!!!! HE LIKES HER!!!!!!!!”
“Yes, but that’s not the issue. No, Shanks doesn’t know what romance is. Mihawk is similarly oblivious, I know, because when I tried to talk to her about it she grossly misunderstood. And she likes him as well, and it is the most frustrating thing I have ever experienced!” The Red Haired Pirates looked and their first mate in shock, because he hardly ever raised his voice in frustration.
Just then steps came running back up the gangplank.
“Guys, look at what I found! A Devil Fruit in the East Blue, that’s so unlikely! Though it’s kind of a lame one…”
And the conversation was shelved for another day, though Benn Beckman would remember to speak with Rayleigh later.
Buggy just gained an even bigger headache, but still gloated in the back of his mind after Shanks left the island about actually having dated a few lady pirates in his time. About ten years later though, he would look back in horror at the mini Shanks and think that his mindset was infectious.
*Swordsman because Dracule Mihawk didn't much care for gender specific titles, and considering the fact that NO ONE matched her with a sword regardeless of their gender she could title herself whatever. To the Women's Association this was a great step forward for Women's rights, for Mihawk it was just her taking the title from the(very male) corpse of the man who'd previously held it and being stubborn about not changing it because its GREATEST SWORDSMAN not swordswoman.