Yeah, Carl is a grumpy old soul, clinging to his cramped homestead, obstructing progress. I do love a good curmudgeon, having known my share in local New Hampshire politics. And Carl wears it well, with his tennis-ball-shoed walker and his square spectacles and his Ed Asner growl.
And yet one of the reasons Up is such an emotionally affecting film is that we see Carl's heartbreaking history, his achingly beautiful love story with his Ellie, in one of the most poignant and real and tearjerking sequences in any movie. Carl comes by his crusty carapace honestly; it's a shell of made of dreams deferred and true love lost and sand slipping through the hourglass.
The later parts of Up give Carl one last adventure, and reawaken his capacity to care for someone else and perhaps even redeem the hopes he had with Ellie. It's Pixar's most adult work, and one that resonates with all of us - life is dreams and reality, and too often we sacrifice what we really want for what we think is required of us. Paradise Falls awaits, and if you're lucky enough to have an Ellie, go while you still can.