At the end of Part I of Goethe's Faust, Gretchen is in prison waiting to be executed.
When [Faust] first meets her, [he] is rebuffed by Gretchen on the street. Mephisto cannot help because she is pure and innocent, so Faust sets off to win her himself.
After meeting Margaret (Gretchen) in Act VII, Faust decides he will seduce her on her own even though she has been to this point, a good and decent woman.
[Gretchen] is a paragon of idealism, purity, and innocence that is corrupted by Faust’s lust. Her virtue gives her an intrinsic aversion to Mephisto, but does not save her from Faust’s desires.
Faust uses jewelry, and the assistance of a neighbor, Martha, to win Gretchen over. She is seduced, and begins to feel guilt over what she has done. To spend more time with Faust, Gretchen mistakenly poisons her mother with a sleeping draught, though this result was unintentional, except as regarding Mephisto. Gretchen becomes pregnant with Faust's illegitimate baby. When her brother discovers what has happened to her at Faust's hands, he is furious.
Gretchen is not responsible for her brother's death other than being involved with Faust.
Gretchen’s brother, Valentine, attempts to avenge her honor after a night of drinking, but Faust kills him, and he and Mephisto flee.
Believing Faust has abandoned her, Gretchen loses her mind. Gretchen is then accused and imprisoned for killing her baby because her baby is found drowned in the river. Faust returns to help her escape, but Gretchen refuses to leave with him, preferring to meet her just punishment. She dies, and Mephistopheles is certain her soul is lost. However, God, in his compassion, rescues Gretchen.
While Gretchen dies at the end of Part I, and Mephisto is convinced she is damned, she is saved by the Lord, seemingly based on her innocence, her unintentional sins, the wisdom she gains through her suffering, and her repentance.
Mephistopheles is surprised at her salvation, but as a being incapable of love, God's love is something he cannot fathom.