Did Fleance become king

No, Fleance didn't become king. In Act 1 Scene 3, the three witches predicted that Banquo's family line would take over the throne of Scotland. In Act 4 Scene 1, they reiterated that prediction. According to the Shakespearean play, Banquo had his throat slit by the three hired, murderous thugs of Macbeth [c. 1014-August 15, 1057]. His son Fleance was supposed to have suffered the same fate. But Fleance managed to escape. The play gave no further information. But information could be had from the stories that Stuart kings such as King James [June 19, 1566-March 27, 1625] I of England and Ireland and VI of Scotland liked to circulate. The King's mother was the decapitated, disgraced Mary Stuart, Queen of Scots [December 8, 1542-February 8, 1587]. She and her Stuart descendants liked to circulate stories about themselves. One such Stuart story was descent from the fictitious Banquo. According to the Stuarts, Banquo's son Fleance fled all the way from northern Scotland, through most of England, and into Wales. There, he married Nesta verch Gruffydd [b. 1059], the daughter of Gruffydd ap Llywelyn [c. 1007-August 5, 1063] and Aldgyth of Mercia [d. after 1070]. Nesta's stepfather, who was her mother's reluctant second husband, was King Harold II [c. 1022-October 14, 1066] of England. According to the Stuarts, Nesta's and Fleance's son Walter traveled all the way back to Scotland. He became Royal Steward to the kings of Scotland. He even managed to marry into the Scottish royal family, and father the long line of kings predicted by the witches. But facts are stubborn, and don't back up the Stuart stories. Fleance's supposed bride Nesta was of noble and royal birth. So her information and that of her family were documented and preserved. She only was known to have married once, Osbern fitzRichard [c. 1055-1080]. She wasn't known to have married again, or to have any child named Walter.