I agree with others that Jane, given what we REALLY know of her (and not the sanitized idealized film portrayals) would have no hesitation about killing Mary if she was on the winning end. She supposedly accepted queenship reluctantly (according to her confession later, after Mary was queen) but her imperious behavior during the 9 days shows that she was very much like any other Tudor. She was also as fanatical a Protestant as Mary was a Catholic - even more so perhaps since Mary still associated with Lords with had conformed to her father's Church, and always hesitated to do anything to Elizabeth despite knowing she was a Protestant - Jane disliked even having Catholics in her presence (according to her letters) and as crowned Queen it would get worse.
I am interested in how Jane killing Mary would effect Mary's image in history. Now everyone calls her "Bloody Mary" for her burnings of Protestants including Latimer, Ridley, and Cranmer (all of whom by the way rallied from the pulpit to Jane, so Mary could easily have killed them as traitors instead of heretics) but in this scenario she never becomes queen and so that never happens. Instead Mary becomes a double victim, of her father, and then of Jane, and a Catholic martyr (and a more innocent one than Mary, Queen of Scots). Given the highly-regarded reputation her mother, Catherine, has to this day even among Protestants (even her tomb in Peterborough now lists her as "Queen of England" - the title Henry denied her- thanks to Victoria) and in her lifetime, Catholics on the Continent regarded Catherine as a saint. Imagine how Mary - actually beheaded - be treated by history. She couldn't be condemned by the likes of John Foxe and future Whiggish historians that glorified Elizabeth. If her kinswoman and governess, Margaret Pole (beheaded by Henry), is now one step away from sainthood, it wouldn't be far off to think that instead of "Bloody Mary", in the present day many would refer to her as "St. Mary Tudor".
As for Elizabeth, if she isn't killed as well, she would always be watched. I doubt she would be married off (remember in Elizabeth's actual reign, she did everything she could to make sure the surviving Grey sisters never married and punished the ones who did), but would always be watched and maybe even live most of her life in the Tower. Catholics might not rally to her side, but disaffected Protestants/Anglicans/Lords/Churchmen tired off the Dudley/Grey families running everything definitely would.
I am interested in how Jane killing Mary would effect Mary's image in history. Now everyone calls her "Bloody Mary" for her burnings of Protestants including Latimer, Ridley, and Cranmer (all of whom by the way rallied from the pulpit to Jane, so Mary could easily have killed them as traitors instead of heretics) but in this scenario she never becomes queen and so that never happens. Instead Mary becomes a double victim, of her father, and then of Jane, and a Catholic martyr (and a more innocent one than Mary, Queen of Scots). Given the highly-regarded reputation her mother, Catherine, has to this day even among Protestants (even her tomb in Peterborough now lists her as "Queen of England" - the title Henry denied her- thanks to Victoria) and in her lifetime, Catholics on the Continent regarded Catherine as a saint. Imagine how Mary - actually beheaded - be treated by history. She couldn't be condemned by the likes of John Foxe and future Whiggish historians that glorified Elizabeth. If her kinswoman and governess, Margaret Pole (beheaded by Henry), is now one step away from sainthood, it wouldn't be far off to think that instead of "Bloody Mary", in the present day many would refer to her as "St. Mary Tudor".
As for Elizabeth, if she isn't killed as well, she would always be watched. I doubt she would be married off (remember in Elizabeth's actual reign, she did everything she could to make sure the surviving Grey sisters never married and punished the ones who did), but would always be watched and maybe even live most of her life in the Tower. Catholics might not rally to her side, but disaffected Protestants/Anglicans/Lords/Churchmen tired off the Dudley/Grey families running everything definitely would.