It's actually my brother's budgie but I'm just too lazy to type.Whoops.
Now I found out 2 triggers for Kaylee fighting Sunshine : Get Out Of The Way!! or when I'm taming Sunshine and Kaylee gets jealous.
But sometimes just plain aggression or unknown reason, they groom each other and feed each other now but sometimes fights pop up like fire-crackers.And Sunshine has his mouth wide open making these little noises while Kaylee um I forgot because I'm worried about my boy.