Now, as said, people have brought this up already. Sans is a character whose shtick is being abnormally good at reading people's faces. Ralsei has spent most of Chapters 1-3 and a little into Chapter 4 lying through their teeth, maybe for good reason. So it makes sense...

But, I think there's more to it than that. However, to actually get into the meat and bones, we'll need to dive into their characters a bit. Now, don't touch that dial, folks, because we'll be here for a while.

Starting with Sans: Besides the decade of mischaracterization, Sans at face value is rooted in what seems to be laziness. Throughout both games, he appears carefree regardless of the situation. Whether it's a child killing everyone but a Froggit, or an eggs-husband showing up.

There aren't a lot of things he really cares at a surface level. Even with the things he does care about, he doesn't seem to care enough. An example of this being that he doesn't fight you in Undertale if you kill somebody, even his brother. Beneath his comedy is an apathy.

But, of course, everyone has a limit. There are points where Sans demonstrates that he cares. Even though he doesn't fight you, he does loathe you for killing Papyrus. Then, famously, he DOES fight you when you kill absolutely everyone, not being able to afford not to care.

In Undertale, he's a character intentionally written to be stuck in a hard place. His background and ties to Gaster grant him far more knowledge than every monster underground. Knowledge that makes living life whilst caring about anything difficult. Or maybe he's just lazy.

Yet, despite it being hard, he still manages however he can through small moments. Whether it's taking a chance and making a promise, "helping" his brother catch the human, or standing in your way during a genocide run. He lives on anyway, even if things don't really matter.

Now, I know, A LOT of this comes from Undertale. Which obviously isn't Deltarune, anagram be damned. But, Undertale as a story is still important to Deltarune.

Gaster only exists as he does because of events in Undertale regarding The Core. Toriel, Undyne, and (seemingly) Asgore share traits with their Undertale counterparts while inside of a Dark World. And, who could forget this interaction with a certain lazybones...

Anyway, speaking of Deltarune, Ralsei: Besides the prophecy, their role in it, and its apparent inevitability. We admittedly aren't given too much to go off of when it comes to Ralsei personally and his views at hand. As The Dark Prince, his role is to guide The Lightners.

Except to him, it really isn't that simple. His deep knowledge of the prophecy means he knows everything to come, and he knows how everything supposedly comes to an end. And that knowledge hurts. It puts him into a figurative corner that he has a hard time stepping out of.

Even as he acknowledges himself as one of Kris and Susie's friends and tries to rise to the title by always trying to keep them happy. He only truly views himself as his role in the story; The Dark Prince. And it's not only towards himself. It's how he sees all Darkners.

He views his own wants to be selfish and wishes to shoulder Kris and Susie's burdens, smiling along the way. As he knows the end, you can assume that he wants everyone to be happy before the tragedy befalls. Especially since the prophecy never changes, despite his best efforts.

That is... until the end of Chapter 4.

When Susie's, "Determination" let's call it, gets through to him. And he decides that he wants to believe again.

And, that he wants to be a better friend towards Kris and Susie. To not just smile all the time.

That is, essentially, the meat of what I think makes the Ralsei and Sans pairing so good. They're people doomed by a narrative because they KNOW how the narrative works. In Undertale, Sans is aware of what Resets are, while Ralsei knows the prophecy's end, the tragedy of it.

But where Sans had already gotten to the point where he does his best to live on anyway in Undertale, Ralsei is only just reaching that point in Deltarune. As of Chapter 4, he's started to embrace what he refers to as his own "selfish desires" and acts upon them.

Narratively, it makes sense. As Sans as a character is essentially made to call people out, and Ralsei is in a place where they want to admit everything and don't at the same time. But, thematically, the fight makes so much sense. I'd argue it's even a better reason for it.

Now, the execution of something like this is a different story. The scenario is entirely based upon how Sans is integrated into the wider narrative. Namely, how much he knows, and also, if he still has any ties to Gaster. Still, I think it could be very, very interesting.

Thread I spent a week procrastinating on banging in less than an hour This is a reference to how I'm literally sans undertale with how I will randomly lock in when I decide I can't afford not to care

Oh, that's a lot of you Thank you for coming to my TedTalk.

Unfortunately, this post taking off has incurred the wrath of Tricky Tony who will now poke fun at this through in-game dialog and will instead make the Chapter 5 secret boss a massive ferris wheel named "the big wheel" who is mad at Kris for shaking it that one time.

@TheAvgCrusader Wait... thats oomf, oomf with a banger thread

@PiggyMageKing

@TheAvgCrusader this would be so so cool but it would probably kill the “sans is from deltarune” theory because how would sans have this knowledge and experience if this is before the underground

@loogiboogi If you're talking about fighting, I think it'd be funny if it goes unexplained until after the fight, to which he answers "video games" If you're talking about how he is as a character? I don't think he'd know about like resets and stuff, but he'd act more or less the same.

@TheAvgCrusader I feel Asgore would also be a perfect fight for Ralsei. Since Ralsei looks like Asriel I can see Asgore hating Ralsei and challenging him to prove himself "worthy" of guiding Kris. Could also give a weapon to buff Ralsei's fire magic if he does end up getting it.

@DaTwilightGamer I do think Asgore would definitely still be the main challenge, not just for Ralsei, but for the entire trio. Sans would be more of a side thing for Ralsei specifically.

@TheAvgCrusader ralsei when a REAL character who hides their feelings behind a smile walks in

@TheAvgCrusader Sans giving papyrus scarf to ralsei as the final superboss weapon to reflect ralsei's growth to not be just kind but be also hopeful for change like papyrus.

@TheAvgCrusader

@TheAvgCrusader Honestly, most of your reasons are why I want SEAM to be the ralsei-focused secret boss. Ralsei fighting a lightner is cool, but using the purple SOUL mode for yarn and mid-battle questions lets "Before you get the PureCrystal... show me why I should hope again" get PERSONAL.