The cut was small enough Farnese didn't notice it until Casca grabbed her hand. A bead of blood was swelling on the tip of her finger. The wound was small but deep. She probably jabbed it on that thorn bush they passed earlier as they were out collecting firewood.
Casca made sympathetic sounds, eyes big with concern. She brought Farnese's hand to her mouth and sucked on the injured finger. Farnese shivered and took too long to pull her hand away.
Of all the things Farnese protected Casca from, she never thought the most difficult thing would be herself.