Heathcliff's not sure what to make of that grin and the idea that Fern would've said yes is bittersweet. Maybe more sweet, though. Probably. He doesn't have too much time to dwell on that or to try and find some clever response about how much she'd paid for Casey, though, before Fern makes her pronouncement.

We'll go together, then.

The boy's heart leaps in his chest and he looks completely floored before breaking into a broad smile. "...We will?"