Deltarune is a game that loves you for experiencing it
i have some hope in my heart that, by the end of deltarune, the message is not going to be "you're awful for having wanted to be a part of this, for imposing, when you're a stranger in these characters' lives".
and i don't necessarily voice this because i believe toby fox would pursue such a moral. on the contrary - both undertale and deltarune are really just love letters to games as storytelling devices, ones that can make you feel and experience things very strongly, to the point of feeling real. yes, all you're experiencing is fiction. no, that doesn't mean it doesn't matter.
it's real because it doesn't make sense if it isn't, with how much it makes you react, live through it. if you were supposed to take fakeness out of the story, susie's approach towards the darkners would not be left as intact as it is. convincing ralsei they can decide who they want to be instead of it being decided by someone else despite being a darkner wouldn't have so much narrative weight. noelle discarding her whole world as as good as fake in the weird route and addressing her role as a character wouldn't be in direct opposition to the normal route's exploration of the relationship between fiction and those who receive it as meaningful.
i instead voice this sentiment because i feel like these facts, very clearly present in deltarune's narrative, get lost in-between somewhere. i see more and more people feeling bad for playing this game they're supposed to be playing. because we are not privy to what happened "that day" and are purposefully excluded from things by being locked in cages or told to look elsewhere, it feels like we're being voyeuristic by being part of the story, like there's no place for us in it.
but that's just not true! the angel is as much a part of the prophecy as the cage, the girl and the prince. the door in the middle of the castle in castletown is adorned with a heart and wings. the place is named after your name. you are as much a part of this as everyone you see on screen. it wouldn't work without you. kris needs you to propel the plot forward as much as you need them to experience the world around you. you're supposed to be here, watching as everything unfolds because it's a story. and stories are meant to be told to someone.
what i feel like deltarune is saying instead of an admonishment for submerging yourself in this fictional world is instead, "this is a story. the story is not "real" but all the emotions it causes when you submerge yourself in it are. and the fact that it's not really "real" doesn't mean you don't have a responsibility, as we all do, to be, above all else, kind. nothing else may matter - but this does, if only to you, because you feel how your own actions affect you".
it doesn't matter if there's one ending. it doesn't matter if it feels like kindness doesn't achieve a thing. kindness is rewarded quietly, through absence of pain that would otherwise replace happiness. the ending might not change but it doesn't need to, since, if you let it, the story is going to change you instead, leaving you different from the you that started playing deltarune. you're a part of it and are welcome through the virtue of it being a story you're open towards experiencing. deltarune is real so long as you let it affect you and cause real emotions in you.
this story wants you there like a tree that wants to be heard when it falls in the middle of the forest. it wants you there to see how it develops and it thanks you for watching the dreams of the characters you see in it.