Bored with her marriage to the "village coward", Rumplestiltskin, Milah regularly goes to the pub where she gets drunk with a crew of pirates. The only reason she even comes home is to look after her son, Baelfire. When she is finally feels too restricted within the small village where she lives in as the coward's wife, she runs away with the pirate crew and has an affair with the captain, Killian Jones. They travel the realms together and have many adventures, which is what Milah had always wanted. Eventually, they go back to the Enchanted Forest for a while, where Killian is confronted by Rumplestiltskin, who has become the Dark One while she was gone. Killian and Rumplestiltskin have a duel, in which Rumplestiltskin uses his newfound dark magic to defeat him. However, before Rumplestiltskin can kill him, Milah intervenes and makes a deal with her husband. If they give him a magic bean, then Rumplestiltskin must leave Milah and Killian alone. On board The Jolly Roger, however, Milah manages to anger Rumplestiltskin. When she says that she never loved him, the deal is off and Rumplestiltskin rips out Milah's heart, before crushing it to dust, killing her. He then chops off Killian's hand, in which he thinks the magic bean is held, before vanishing with it. Upon opening the severed hand, Rumplestiltskin realizes that he had been cheated.
Killian Jones, now known as Captain Hook, goes on a vendetta against Rumplestiltskin as he wants revenge for Milah's demise and the loss of his hand, calling Rumplestiltskin a "crocodile" due to his appearance as the Dark One back in the Enchanted Forest.
In the Underworld, Milah meets Killian's current girlfriend Emma Swan, as well as being confronted by her murderer and ex-husband. Although Milah initially expresses disdain about Emma's romantic history with both Milah's son and former lover, she helps Emma and Rumplestiltskin into Hades' domain to rescue Killian. However, while Emma goes forth to save Killian, Rumplestiltskin - who is working for Hades - betrays Milah and pushes her into the River of Lost Souls.
- Peter Pan (deceased father-in-law)
- Fiona (deceased mother-in-law)
- Rumplestiltskin (widower)
- Killian Jones (ex-lover)
- Baelfire (deceased son)
- Gideon (step-son)
- Henry Mills (grandson)
- Cinderella Mills (grandaughter-in-law)
- Lucy Mills (great-grandaughter)
- Milah's husband, her other lover and her son are respectively based on the crocodile, Captain Hook and one of the Lost Boys from Peter Pan.
- Hook gets Milah's name tattooed on his remaining hand.
- S2, E04: "The Crocodile" (flashback)
- S2, E14: "Manhattan" (flashback)
- S5, E10: "Broken Heart" (flashback)
- S5, E14: "Devil's Due"