|First Appearance||Terminal (mention)|
|Last Appearance||Flatline (mention)|
Madeline Black (no official spelling given) was the older sister of Eugene Black. She suffered from leukemia. According to Eugene, she used to be a very strong figure and was the only positive element of his life. Despite her condition, she apparently managed to keep a positive attitude.
She was treated by a Dr. Harris and was unable to leave the hospital. While Master Chief and Arbiter have never met her, Eugene mentioned her to Arbiter when they first met and Arbiter asked about her during their second meeting.
Madeline eventually suffered a cerebral hemorrhage, and passed away. Dr. Harris called Eugene, and informed him of her fate.
Eugene told Arbiter that Madeline, despite her illness, kept a good sense of humor about her condition, which he finds uplifting and hopeful.