[He supposes he can understand this, in his own way-- he chose to remain behind while everyone else went to the surface for bigger and better things, after all. But that was just as much a self-imposed punishment as it was taking time to rest from it all.]

Well, you do you! But when you're trying to get sand out your ears, you're going to be thinking, "I slayed a cosmic monstrosity for this?"

[He's not sure what else to say, but he has listened attentively to her words. What an interesting person... she's lived such a different life than the rest of them, it seems.]

Oh, silly me! I didn't introduce myself! You can just call me 'Flowey'.