Al is a skinny old woman who, as her name suggests, is blind. Her origin is never explicitly elaborated. It is eventually revealed that she was somehow involved with British intelligence, although in what capacity is unknown. She was already blind by this point and has been most of her life. Wade Wilson, the mercenary who would eventually become Deadpool, was hired to kill her in Zaire where she was stationed. What actually occurred is unknown, but apparently Wilson killed everyone around except her, allowing her to flee. Years later, after he had gotten cancer, received a healing factor from Weapon X, gone insane, and became Deadpool, Wilson met up with Al again and captured her.
About two years into her imprisonment, Deadpool left on a long assignment, and Al decided to leave for a friend's in Maine. She escaped, trekked across the country, and when she arrived at her friend's house, Deadpool was waiting for her, her friend tortured nearly to death in front of his dogs.
There was a bizarre relationship between the two, with Al acting as a cross between a prisoner, friend, housekeeper, Greek Chorus and mother-figure to Deadpool. At times Wade could be unbelievably cruel to Al. He would frequently insult her and play cruel pranks, taking advantage of her blindness. He forbade her visitors and would kill anyone who tried to help her escape. On the rare occasion when she angered him, he would put her in the Box, a small, booby-trapped room filled with sharp objects (although he never actually locked the door, counting on her fear of him to keep her imprisoned). He also forced her to cook and clean for him, and dangled the prospect of freedom in front of her only to snatch it away.
On the other hand, Al seemed to wield a subtle authority over him, and seemed to be the only person who was not afraid to stand up to him. The pranks never bothered her, as she was more than clever enough to get back at 'Pool (putting laxatives in his food was a favorite), and she was even sharper than he was when it came to insults. When the series opened, Al had already been with Wade for years, and a sort of peace had developed between them. Al seemed grateful for having food, a roof over her head, all the Matlock she could "watch," and safety from those who wanted her dead, all in return for doing a few chores and putting up with Wade's twisted sense of humor. She was his closest confidant (even more so than Weasel) and trips to the Box had become so infrequent as to be unheard of. She held an immense debt of gratitude for Deadpool for saving her life, and it gradually became clear that she was sticking it out with him because she believed that he had the potential to become a truly good person, and she hoped her influence over him would encourage him in that direction. She also hinted that she had a rather dark past, and felt that redeeming Wade would help her make up for past deeds. They shared an adventure together through time, where Al ended up impersonating May Parker. She seemed as much a parent as a prisoner to him, and he even gave her Deuce the Devil Dog as a present.
However, Deadpool soon hit a low personal ebb, and the peace between them became strained. This culminated in a trip to the Box after it became clear that Blind Al had been keeping visits from Weasel a secret from him. She got her revenge however, by coldly shunning him, and referring to him as "master" to highlight his cruelty. The guilt he felt was enormous, and he eventually declared her a free woman. She refused to leave so he teleported her away from him, preferring not to keep her imprisoned, even of her own free will.
After Deadpool saved the world from the S'met'kth, he dropped a medal that Blind Al had given him, which she claimed was from a soldier she had an affair with in World War II. Captain America picks up the medal, remembering he had given it to Althea. On the back of the medal is inscribed, "To Althea...Thank you for reminding me what it means to be a hero...Ever yours...Steve."
Since then her appearances have become much more sporadic, although it is clear that she and Deadpool are still in contact. Deadpool later approached her to validate his plan to restore his reputation by battling Taskmaster.
An elderly, blind woman, Al maintained her quick wit despite her years-long imprisonment. It is assumed she went through combat training in the past. She also has height sense in areas familiar to her, once saving Weasel's life while in "the Box".