Hearing this about his parents and how awful Damian was, Kale began to get very angry. This caused the plants to grow rapidly around his and he and began to fight with Damian. Both using their powers, Damian tried to fight back but his weather powers were no match for Kale's anger and desperation.
Seeing that he couldn't win Damian was forced to yield and he broke down, regretting all of his actions begging Kale to forgive him. He said that he realized how selfish and dumb it was of him and he had to live with it now.
Kale had learned a lot from his time alone while he was an outcast. He knew that even though he was mad now he realized that it wouldn't fix the fact that his parents were gone. He decided to forgive Damian and let him live with the guilt of what he had done. Kale went on to live a great life, using his powers for good.