Easy answers, things they don't need to put heavy effort into thinking up answers for, or need to glance at him to gauge a reaction for their replies. School's nice; all monsters are their friends, really; homework's no fun but Toriel's good at teaching.

The sudden real question stops them before they can step through the gate of their nice little picket-fence.

Sans-es are always observational. Frisk glances at him and shrugs. "...Not everybody likes naps as much as you do," they say dryly.