Celia, a.k.a. Aliena, is the daughter of Duke Fredrick and the dearest friend of Rosalind. She goes into voluntary exile in the Forest of Arden with Rosalind and Touchstone the jester, and there falls in love with Oliver, the eldest son on Rowland du Bois.
Celia is introduced alongside Rosalind as a voice of wisdom and consolation. She encourages Rosalind in her sadness, but also checks her gidiness when she resolves to be happier. She is also shown to be very intimately acquainted with Touchstone. When Rosalind and Orlando fall in love a little later, Celia is against it and tries to make Rosalind believe that she is kidding herself.
When Rosalind is banished from the court, Celia decides to enter exile with her cousin, and is largely responsible for their plan. She smears dirt on her face to appear different in skin tone. She also assumes a false name, Aliena.
Celia nearly dies from exhaustion on the trek from the court to Arden, and is thus willing to strike a deal with Corin in to obtain food and rest. After recovering, she spots Orlando hanging bad poetry on the trees, and teases Rosalind about itmfor a brief time until she finally reveals who it is. When Rosalind forms a comlicated plot to get Orlando to woo her male alibi, Celia is critical of her, but can make no dent in Rosalind's love or determination.
When Oliver appears as a messanger from Orlando, he and Celia are instantly taken with one another. When they are married in the play's final scene, Hymen remarks that the pair are "heart in heart."