At the beginning of the exam, Natsu wanted Erza as his opponent.
Erza stated that she realized something important, which is, It is better to live for your friends than dying.
Natsu Banished Fanfic
When they returned back to the Guild, Erza and Natsu decided to have a battle.
Description: Also, when Erza dressed as a nurse to heal everyone, Natsu was seen in the long queue of males, awaiting his treatment. Angrily, Natsu refused to meet the demands of Phantom Lord, along with Erza.