If you haven't; please refer to her previous (and first) appearance. I'd planned on doing more with her at the time, but Eli's cannon quickly got more uh...'inspired'.
Initially she was to have a highly inappropriate crush on him that never went beyond getting a bit handsy (she wouldn't want to hurt him) in service of contrasting Voight's abuse.
Over time I lost interest in the idea and wanted Eli to have at least one adult in his life he could trust. She unfortunately fell to the wayside because I liked drawing the dynamic between Eli and Voight more, but I still want to depict the softer, happier moments in the bun's life, many of which Mia is responsible for.
If she ever finds out about Voight's actions she'll set his house on fire with him in it.