Sure, I’d be happy to. In terms of characters, we have:

• Brienne is the Knight of the Woeful Countenance. Quite literally, given what Biter does to her face. In a broader sense, she’s a knight who isn’t a knight, yet is the only one who holds to the true ideals of knighhood in a world of cynics. 
• Pod is Sancho Panza. The hapless yet infinitely loyal squire who follows his knight to the end, even when that takes him into hideous danger.

In terms of plot arcs, Brienne spends the whole of AFFC engaged in an impossible quest: Jaime has given her his sword and sent her forth to “make good our stupid vows to your precious dead Lady Catelyn“ – but Brienne finds herself fruitlessly chasing rumors. She tries to track down Dontos Hollard, but finds Shagwell, and she never learns that Dontos Hollard is dead and that Sansa is in the Vale. She tries to track down Sandor in the hopes of finding Arya, but she doesn’t recognize Sandor when she comes across him, and ends up finding Rorge instead, who’s been pretending to be the Hound. And even if she had found the Hound, he doesn’t have Arya anymore.

But despite her task being practically impossible, despite having every rational reason to give it up, Brienne refuses to compromise her ideals. No matter that Shagwell ambushes her three on one, no matter than Rorge shows up at the inn with “Seven, Brienne thought again, despairing. She had no chance against seven, she knew. No chance, and no choice,” she keeps fighting. 

And that’s the very heart of Don Quixote’s creed.