Cava

"When you and Nolan started I knew about it. He told me. I looked you up on the internet and there it was. I mean, everything about your family and your parents taking the money. Nobody here put it together because you were using your middle name at the time. And I told one person and... Once it was out it just spread like... Like wildfire. And then everything with the reporters and the press and the media and - now Mason knows and I'm sorry. I'm the rat. Ava, please, say something."

- Caitlin confesses to Ava

Cava is the friendship pairing between Caitlin Park-Lewis and Ava Jalali.

Timeline
First Relationship (fake friends):
 * Started: One-year prior to "Pilot" (101)
 * Reason: Nolan began dating Ava around the time Caitlin ended things with him. He told Caitlin that he was dating Ava, and she joined his "perfect posse". He blackmailed Caitlin into being his fake public girlfriend. As a result, Ava and Caitlin were fake best-friends.
 * Ended: Pilot (101)
 * Reason: Nolan was killed and there was no longer any reason to remain fake friends.

Second Relationship (friends):
 * Started: "...If One of Them is Dead" (102)
 * Ended: "The Ghost Sonata" (103)
 * Reason: Caitlin admitted to Ava that she was the one who told the school that Ava was a Jalali. Her "ratting out" Ava caused the latter's Freshman year to be a living hell for her. Unable to forgive or forget, Ava ended their friendship and kicked Caitlin out of her apartment.

Trivia

 * Both dated Nolan Hotchkiss for a length of time, however, Ava truly loved Nolan while Caitlin grew to loathe him.
 * Caitlin brought Ava a present from Nolan since it was mistakenly given to her by Claire.