Spencer and Aria are part of the A-team.
They were both heavily harassed by Alison. Ali threatened Spencer to tell Melissa about her and Ian. She also threatened Aria into telling her mother about Byron’s infidelity and if she didn’t, Ali would do it herself. Hanna was too naive to go up against Ali, and Emily was too in love with her which leaves Spencer and Aria to stand up for themselves. Also, the whole ‘waking up after drinking’ is planned by Spencer and Aria (notice how it’s almost routinely done, and Aria and Spencer are always the first to wake up, on both occasions.) They only meant to hurt Ali, but now they’re playing it off as if they are also being victimized.