When Lisanna comes back the whole guild had a party but when they were having a party everyone was drunk a girl with a staff asked Lisanna to touch her staff so she did the girl went to Lucy next and the staff glowed Gold and White Color buy little did they know that staff can make people pregnant if they both liked each other and Lucy touched the staff and she got pregnant with twins. So Lucy left the guild because she found out she was pregnant and left for 7 years to take care of the twins. Fairy Tail does not belong to me but to the owner.