Somehow, they'd expected more of a reaction than that.

"...guess we will."

Frisk considers what else they'd tell somebody new. Chara already knows they're in the sky, about the timeline stuff, about the monsters here...

"An' watch out in the gardens," they say finally. "There's a trap door in the garden. 'F you fall, you can't get up without help again." That's something they should probably know, even if they hadn't heard of anyone else falling in.