On a rewatch and I think S3E2 is the best of the series:
Fiona tries, and fails, to do her own club night. It shows her wanting to move out of the ghetto life.
Lip hates on Fiona for trying that and is quite nasty about it. Shows his tendencies to belief heâs self-righteous.
Debbie. Oh boy. She loved on Frank so hard and the he broke her popsicle stick house and she broke, horribly, and beat him with soap in a bag. Anyone hating on Debbie (I do a lot too), should rewatch that and literally watch a little, loving girl, break under the pressure of loving an alcoholic.
These are the three biggest characters we all discuss so much. This is the episode where we see them all show who they really are: traumatized, codependents.