Myra is an Erudite born along with Will and Edward, but later chooses Dauntless at the Choosing Ceremony. Myra was the girlfriend of Edward, a strong and effective fighter. Despite this, however, Myra is the complete opposite of him, being a weak and frail fighter going down in a fight with Will in less than three minutes.
Myra had the lowest rank on the First Stage of the initiation.
After Edward is attacked by Peter Hayes and Drew which results in the loss of one of his eyes and him being cut from Dauntless initiation, Myra voluntarily follows him, ending in both of them being factionless.
When her fellow Dauntless initiates Drew and Molly Atwood get cut due to their low rankings, Edward almost kills them for being affiliated with Peter. Myra willingly leaves Edward after this, claiming that she "couldn't handle the tension," implying that she could not bear Edward's vindictive and dominating nature.
Christina describes Myra as being one of the only "nice" initiates left, as the rest of them were killed (excluding Tris and herself).