(Been thinking of this for a while, ever since I saw what Flowey says if you start the game after a true pacifist ending, but I felt like writing it out. Really just using Undertale to explore a concept here though.)

Hey...

Look, I know what the flower said. Everyone is got their happy ending. To go back on that, to rip them out of the timeline and take them back would ruin that. You should know by now, the other possibilities? They aren't so happy. And somethings taint you, somethings are inescapable. Even if you cheat, you still would know you did it. Maybe you don't care. So yeah, taking away that happy ending seems more then a little cruel.

But... Something's bugging you isn't it? Maybe more then one something. Maybe not least of all that happy or not this is still a ending. Yeah, you could leave everyone to their happy life. Except... Can you? What happens to the characters when the story is over? How do you even know if they are really happy? Or heck are even still really there? This is the end of the timeline for you... what if it's the end for everyone else too? Just frozen visions of moments and... nothing after. And really, not everyone is happy, The Empty Vessel, The Jester of Sorrow, The Scion of Hatred, The Forgotten, where is their happiness?

The future isn't written yet, maybe it never will. This is where time stops. Maybe all stories must end. You can go back, to try and rip through reality, find secrets that may not exist. I wouldn't really blame you, even if others might. Isn't that better then a frozen future even if it causes pain? Maybe. Or...

Or... You could look at another path in the void of possibilities, maybe even write a future yourself. Go beyond the timeline you knew, You aren't the only one looking. Maybe, just maybe, if all of you keep a light burning, someday a new path will open forward. All stories must end. Or so they say. But for every ending maybe a seed for a new beginning is planted.