The Darkling's desire for Alina
The Darkling's desire for Alina might in some ways symbolizes the destructive elements of love. Although the Darkling claims to love Alina, he hurts the people she cares about the most and destroys her home. As such, his love for Alina is certainly not healthy or positive.
The Firebird
The Firebird represents the potential for Alina to gain the strength she needs. At first, she believes The Firebird is an amplifier, who can fortify her powers and help her to stop The Darkling.
Mal's sacrifice
The fact that Mal is prepared to sacrifice himself for Alina symbolizes how much he loves her. Throughout the novel, Mal expresses his strong feelings towards Alina, which he proves by his willingness to die for her.
Mal as the amplifier
Towards the end of the novel, it is revealed that Mal is in fact the amplifier. This symbolizes the fact that Mal's friendship, love, and support strengthens Alina.
The defeat of the Darkling
Although it is not certain whether the Darkling is truly killed at the end of the novel, he certainly lost the battle. This represents the triumph of good over evil.
