I'll always be watching over you

Lucy lost her older brother at the age of 8, before her brother (Laxus) die he gave Lucy a phone and told her that if she ever feel sad or lonely,she could contact Daisy.What will happen to her life wend she has 16 years old?What role does sting have in this story?i got inspired while reading dengeki daisy, it really is a good manga. So you most read it