Both Marianne and Connell, at different points in the novel, get their faces bloodied. Someone mugs Connell at Trinity; Alan assaults Marianne back in Carricklea, breaking her nose. Their physical injuries lead to a confrontation with their invisible emotional injuries and to a rupture in their usual daily patterns. 

After being mugged, Connell shows up at Marianne’s apartment so that she can pay his taxi fare and take care of him. Drunk as well as injured, he acts more hostile than usual toward Marianne’s boyfriend, Jamie. At the same time, he informs Marianne that he has a new serious girlfriend, a medical student named Helen. Connell is raw and lost; he stands out starkly from Marianne’s more socially insulated friends. His bloody face dramatizes both of these underlying realities. Marianne’s broken nose forces a confrontation between Connell and Alan, helping her to finally break away from her family and to admit the extent of her need for Connell. 

Marianne’s and Connell’s physical injuries also show their underlying similarity as characters. Both vulnerable and unconventional, they often find themselves colliding with the world, literally and metaphorically.