Who am I

Once there was a girl on this forum. She had a brother who liked making fun. So when the girl forgot to logout he wrote all nonsense with her name. The girl didn't like it. So another time(not so long ago) the brother decided to make an account on the forum with another name than his own. He would somehow try to become his sisters friend on the forum without her knowing who he really was. But the girl was clever and saw that it was her brother because of the way he wrote. So his plan didn't succeed. I have something to confess... The girl is Lydia and the boy is Stefan(me).