All that we know about Halle comes in bits and pieces. He's a devoted son, able to buy Baby Suggs's freedom by farming himself out as a laborer. He seems like a good husband since Sethe never complains about Halle. Sure, he never showed up for their planned escape from Sweet Home, but Paul D clears him in Chapter 7.
We know Paul D admires Halle for his inner manliness (24.220). To him, Halle's someone slavery can't bring down. That's why it's so surprising to Paul D and Sethe that Halle basically becomes catatonic, with butter on his face, after he sees Sethe get raped.
But it makes sense that Halle would become so broken. Halle's greatest strength as a character is his devotion to the women in his life, so as long as his ladies are vulnerable, so is he.