After surviving her fall Harley Quinn decides that she has to repay society for her wrongdoings and that she especially has to repay Batgirl for saving her life. Though reluctant at first, Harley is eventually allowed to replace Tim as a Batfamily member in exchange for helping to rehabilitate the ex-Robin.
Psalm of the Lark can be read here
Psalm of the Lark provides examples of:
- Alternate Universe Fic: Harley joins Batgirl after the events of Return of the Joker
- Alas, Poor Villain: After seeing Harley Quinn fall to her death, Barbara mourns her because she couldn't save Harley. Of course, it's just a Disney Death.
- Decomposite Character: Jason Todd is mentioned as a Posthumous Character. In the DCAU, Tim is a Composite Character of the comic's Tim and Jason.
- Dirty Kid: A group of elementary-aged kids goggle at Harley and Barbara cuddling after they accidentally park in front of their school.
- Disabled in the Adaptation: It's mentioned that Harley wears prescription contacts for her vision. In canon, it's never explained why she only wore glasses as Dr. Quinzel.
- First-Name Basis: At first Barbara dislikes Harley calling her by her name, and especially by an Affectionate Nickname. It takes a while for them to get on a First Name Basis.
- Full-Name Ultimatum: Barbara calls the Joker "Jack" when breaking the news of his death to Harley. It's the first sign that something is wrong.
- Gayngst: Harley admitting her feelings for her really confuses Barbara at first. Barbara struggles with wondering if maybe she's bisexual or even gay.
- HeelFace Turn: After the Joker's death, Harley turns over a new leaf. She becomes a part of the Batfamily as "the Lark".
- If It's You, It's Okay:
- Prior to Harley, Barbara never fancied the idea of dating a woman.
- Harley mentions that she's not lesbian or bisexual. She just likes one woman in particular.
- Setting Update: BTAS took place in the '90s while Psalm of the Lark is contemporary 2000s. There's a joke where Harley claims it's the 1990s, only for Barbara to mention it's been a decade since then.
- Slash Fic: It doesn't appear until later on but there is a Barbara/Harley element to the story.
- Slipping a Mickey: At a party, someone (more specifically, Tim) slips Smilex into Harley's drink. It leaves her drugged and crazed for several weeks, to the point where she's temporarily put back in Arkham.