how does bigger handle fear?

Bigger handles fear in fight or flight mode. He has always handled the fear and anxieties of social injustice this way. We can see this fear personified in the way he deals with the rat:

A huge black rat squealed and leaped at Bigger’s trouser-leg and snagged it in his teeth, hanging on.

"Goddamn!" Bigger whispered fiercely, whirling and kicking out his leg with all the strength of his body. The force of his movement shook the rat loose and it sailed through the air and struck a wall. Instantly, it rolled over and leaped again. Bigger dodged and the rat landed against a table leg. With clenched teeth, Bigger held the skillet; he was afraid to hurl it, fearing that he might miss. The rat squeaked and turned and ran in a narrow circle, looking for a place to hid; it leaped again past Bigger and scurried on dry rasping feet to one side of the box and then to the other, searching for the hole. Then it turned and reared upon its hind legs.

"Hit ‘im, Bigger!" Buddy shouted.

"Kill ‘im!" the woman screamed.

The rat’s belly pulsed with fear. Bigger advanced a step and the rat emitted a long thin song of defiance, its black beady eyes glittering, its tiny forefeet pawing the air restlessly. Bigger swung the skillet; it skidded over the floor, missing the rat, and clattered to a stop against a wall.