Nesta is portrayed as guarded, stubborn and hot-headed, having built an impenetrable facade over her emotions, heart and mind. Nesta is crucially honest, direct, and unafraid. Feyre believes that she sees and feels so much that she must shield her heart with the fiery anger she emits. Nesta is fiercely loyal to those she loves, namely Elain, and would do anything to protect them.
(Taken from ACOTAR Fandom. Book Featured: A Court of Thorns and Roses by Sarah J. Mass)