Alex's Tears represent.

Alex's tears represent her own personal connection to fairy tale land as well as her emotional and sympathetic side. When the Evil Queen stands in front of her mirror after Conner breaks the vial of fairy tears, she notices something about Alex. The queen then proceeds to tell her story of how she became evil, causing Alex to cry out of sympathy for the queen. The queen takes some of Alex's tears and uses them to activate the Wishing Spell for herself. This proves to Alex and Conner what they had been suspecting; that they are part of the fairy tale world as both Alex and the Evil Queen could see Alex's wings in the mirror.