Spoilers for Daredevil Season 3 ahead. Sister Maggie may seem like a mysterious figure from Matt Murdock's past on Daredevil, but Marvel comics fans know there's more to this character on the Netflix series than meets the eye. When Matt discovers that Maggie is his mother on Daredevil, he goes to the man that raised him in her stead — Father Lantom. Their talk in Episode 9 reveals more secrets about Matt Murdock's past, secrets that even the Devil of Hell's Kitchen didn't know.
While praying, Maggie reveals that she is Jack Murdock's ex-lover, and Matt's mother. Of course, Matt's super hearing gave her up, and he learned the confession. He doesn't confront his mother. Instead, he goes directly to the man he trusted most.
Did Maggie know this was going to happen when she spoke her secret out loud? It's kind of a cowardly way to tell someone something important, if that is the case. When Father Lantom tells her that Matt knows, she's devastated, and later she tells Karen that he found out on his own. I'm not buying it, but we can take her word for it. She feels guilty, and offers to help Karen hide from Fisk, but it's not enough.
A flashback shows how young Maggie met and later lost Jack. Was it shame that kept her and Jack being together after Matt was born, or Father Lantom himself? Whatever happened, Matt was raised to believe that he was an orphan after his father died. It's a personal betrayal from the people he was closest to — and on a larger scale a betrayal of the Catholic Church that the man behind Daredevil has been devoted to for years, ultimately designing his whole moral code around and those values.
At first, Matt is embarrassed that he didn't figure out who Maggie was sooner, as the truth had been in front of him for his entire life. "Then I remembered that it had been in front of you for even longer," Matt says to Lantom when he confronts him. "From the beginning, and we've talked so much about truth. You and I."
During the episode, Matt debates with his father's memory over which of his family's sins is the worst. Jack could have told him who his mother is, and where to find her, as well. Matt's father, in his mind, claims that Maggie left the both of them because of the darkness she sensed in them. However, that's stress and fear talking. Maggie's prayers may have expressed worry over how much Matt was like his father, but it doesn't excuse what happened to her son. All of the adults in his life kept the lie that his mother was out there over, and over, and over.
The consequences of this lie are dire, too. After losing faith in more ways than one, Matt decides that he has to give up the moral code that was guiding him as a vigilante and kill Wilson Fisk. His trip into darkness just got a little deeper.