Okay, I had a random thought along these lines recently. And this is NEVER going to happen. This idea is SO STUPID, that even Oda would shake his head in shame at it. But, I can't get it out of my head, so I'm inflicting it on all of you. I'm sorry.
Is it possible that Roger...stole Garling's girl?
In the latest chapter, 1158, we finally get a glimpse of Shanks and Shamrock's mom living on God Valley. And all we really see of her is her long hair, which is supposedly red.
And Rouge also has long hair. Which is..pink. Or pinkish-blonde, depending on the shading. Now, here's a bit of obscure trivia, pink is NOT red. But, it is within the spectrum of "redness", sorta. So...uh...it kind of fits, if you squint...and if you're a bit colorblind. Look, Oda has retconned hair colors before, and I could see him doing so again here, maybe. Ju Peter was blonde for decades, before Oda revealed his real hair color was white on a volume cover. Rouge's "manga-official" hair color could turn out to be red, with the anime colors being retconned. And "Rouge" IS another shade of red, just saying.
Rouge also has a flower in her hair. Which is often times visual shorthand for being a "foreign island girl". Mind you...this is One Piece..and technically ALL girls in the entire world are "island girls". But, I don't know, maybe this is a sort of hint from Oda that Rouge is more "foreign" than most? Some special race or bloodline?
So, is it possible that Shanks' mom is actually...Portgas D Rouge?
Now, we've only ever seen her living on Baterilla. But, there's nothing saying she's originally from there. And we still haven't seen how Roger met Rouge in this ongoing Elbaph flashback yet. So, we can probably say that Roger never met Rouge until during or after God Valley.
So, is it possible that Roger met Rouge on God Valley, saved her, and then fell in love with her?
We know that Shanks is being called "The Child of Destiny" for some reason. That MIGHT be because of his unique bloodline. A bloodline that me MIGHT have inherited from his mother's side of the family. Since Garling doesn't seem to be all that special among Celestial Dragons, even if he is strong and ambitious.
So, is it possible that Roger hooked up with Rouge in order to father his own "Child of Destiny"? A "Child of Destiny" who carried his own bloodline along with this special "Portgas" bloodline, while he kept a eye on the original "Child of Destiny" by adopting Shanks. Trying to "overwrite" one destiny with another one? It might even explain why Roger adopted baby Shanks. He was hooking up with his mom.
Could Shanks and Ace be step-brothers?
Could this also explain why Gloriosa is in her "bad timeline"? Roger didn't end up choosing her, not because he loved someone else, but because he was USING someone else to further some mad scheme of baby-fights? Did Roger actually ever love Rouge, or was he just obsessed with securing his legacy? Maybe Roger was "destined" to end up with Gloriosa, and fathering Ace was his own "bad timeline"?
And...fine, if you don't like that idea, here's a slightly different one.
Could twins run in the family?
Shanks' mom gave birth to twins...obviously. And that happens more often in families with a long history of having twins. So, is it possible that Shanks' mom had a sister on God Valley? Roger might have ended up hooking up with the twin sister, Portgas D Rogue. And Shanks' mom might be...Portgas D Rojo or something.
And if THAT'S the case...could Ace have a secret twin out there, somewhere? Could there be...a Portgas D Deuce?! That would be a way to bring Ace back, without actually bringing Ace back. It'd just be a character who looks exactly like Ace. And don't you say that's impossible, because Shanks' evil twin has opened that door, and there's no closing it now!
So, is it possible that Roger and Garling actually ended up hooking up with the same girl? Or maybe they're just both hooking with identical twin sisters?
...No. This is all nonsense. I KNOW it's nonsense. Again, Rouge's hair isn't even red! I don't know WHY this stupid idea won't get out of my head. But, now it's out there. So, I can move on!
(...But, again, if this actually ends up happening, I'm TOTALLY taking all the credit for thinking this up. I reserve the right to be smug that I called this, even though I don't even think this is a good idea.)