Alison threatened to tell on Spencer when she spotted her kissing Melissa's boyfriend Ian.
And somehow 'A' knew all about Spencer's secret!
History repeated itself when Melissa witnessed fiancé Wren kissing Spencer in her bedroom one night.
These sisters were literally in competition over everything!
Alison witnessed Aria's dad having an affair with his student Meredith.
'A' knew all about the secrets and lies in Aria's life, both her dad's affair and her blossoming relationship with Ezra.
Aria was terrified that her relationship with her English teacher would be exposed.
Poor Aria had to sneak around so much in Season 1!
Alison seemed to be the only one in the group who knew that Emily was into girls.
Until 'A' began playing games!
The fear of coming out put a strain on Emily's relationship with Maya.
And Emily coming out hit the Fields family pretty hard, but luckily her friends were super supportive from the very beginning.
Hanna's eating habits were always watched very closely by Alison.
And 'A' knew just how to hurt Hanna where she was most sensitive.
Hanna was living much more healthily and happily now, but was still willing to do whatever it took to save her mom.
Ashley and Hanna Marin have always been an incredible team! We have so much love for them.
And this was just the beginning for the Liars...
As 'A' was about to uncover a whole lot more!
Who do you think 'A' messed with the most in Season 1?
Let us know in the comments.