Alternate history - Tudor England
I love worldbuilding alternative history. One world that I'm currently building is about (the descendants of) an English orphan named Fanny who's born around 1480 and how she/they affect the world around them over time.
The first major difference caused by Fanny: Prince Arthur doesn't die in 1502. Here's the timeline from there on. I'll try to share the family tree some other time if there's an interest for it.
Spoiler: I've made it as historically realistic as I could, so there's some cousin marriages, childhood deaths, young marriages etc here and there. I will be leaving some births and deaths out of the timeline because they're irrelevant but there is more in the family tree.
1506 Prince Arthur of Wales and Princess Catherine have a daughter, Princess Mary.
1509 King Henry VII dies and passes the throne to his son Arthur. King Arthur is sickly so he writes a clear line of succession prioritizing his daughter over his brother and gets it approved by Parliament.
1510 King Arthur I dies and passes the throne to his daughter Mary. Queen Mary is only four years old so she needs a regent. Queen Mother Catherine and Prince Henry the Duke of York both want to be the regent and the support of the nobles is split between them. Henry gets betrothed to the daughter of the Duke of Buckingham in order to sway support his way and becomes the regent. Catherine starts holding yearly Easter and Christmas gatherings to have as much influence as possible so she can still keep Henry from doing anything that goes against her daughter's best interest or the Vatican's best interests. A silent feud between the two develops.
1513 Prince Henry the Duke of York marries Elizabeth Stafford, the daughter of the Duke of Buckingham.
1517 Prince Henry the Duke of York and Elizabeth Stafford have a son, Henry.
1520 Prince Henry the Duke of York, as regent, arranges aan betrothal between Queen Mary and her cousin Prince Louis of Portugal.
1522 Queen Mary and Prince Louis get married. Queen Mother Catherine convinces the nobles to end the regency, so Prince Henry is no longer regent. Queen Mother Catherine starts organizing larger East and Christmas celebrations for all the nobles and intentionally keeps Prince Henry out of all the smaller, more intimate gatherings.
1523 Prince Henry the Duke of York and Elizabeth Stafford have a daughter, Elizabeth. The mother dies shortly after giving birth.
1527 Queen Mary and Prince Louis have a son, Prince Arthur.
1528 Prince Henry the Duke of York marries Margaret Fitzalan, the daughter of the Earl of Arundel. The same year they have a son, William.
1535 Prince Henry the Duke of York, unpopular due to being left out of many celebrations, makes an alliance with the Earl of Oxford by agreeing to betroth both his son Henry and his daughter Elizabeth to the Earl's children.
1537 Queen Mother Catherine passes away. Henry Tudor, son of Prince Henry the Duke of York, marries Anne de Vere, daughter of the Earl of Oxford.
1540 Elizabeth Tudor, daughter of Prince Henry the Duke of York, marries John de Vere, son and heir to the Earl of Oxford.
1541 Queen Mary arranges a betrothal between her son, Prince Arthur, and her husband's niece, the Habsburger Princess Joanna, to arrange an alliance with Joanna's father Charles V of the Holy Roman Empire.
1543 Prince Arthur and Princess Joanna get married.
1548 Prince Henry the Duke of York dies and passes the dukedom to his son Henry. The new Duke continues to be left out of the more intimate gatherings organized by Queen Mary, continuing the family rift into the next generation. The Earl of Oxford and his family however, including Elizabeth Tudor, do get invited, causing a rift between the two families.
1549 William Tudor, son of the now deceased Prince Henry the Duke of York, marries Anne Bourchier, daughter of the Earl of Essex and his wife Edith Stourton.
1558 Henry Tudor, the second Duke of York, attempts to repair the rift between him and the new Earl of Oxford - Elizabeth's husband - by arranging a betrothal between his son Henry and their daughter Elizabeth.
1560 Queen Mary I dies and passes the throne to her son Arthur. Henry Tudor, son of the second Duke of York, and Elizabeth de Vere, daughter of the sixteenth Earl of Oxford, get married.
1568 King Arthur and Queen Joanna have a daughter, Princess Mary. A maid of honor of Queen Joanna - Elizabeth Percy, daughter of the Earl of Northumberland - uncovers a plot by Henry Tudor the second Duke of York to overthrow King Arthur and take the throne for himself. A powerful majority of nobles supports him due to concerns about a female heir from a foreign house. To protect his reign and his daughter, Arthur arranges a betrothal between Princess Mary and the five year old Henry Tudor, grandson of the second Duke of York. He also writes a clear line of succession putting the descendants of Prince Henry the first Duke of York after his own children.
1569 William Tudor, son of William Tudor and Anne Bourchier, and Elizabeth Percy, daughter of the Earl of Northumberland and maid of honor to Queen Joanna, get married.
1972 Both Princess Mary and her betrothed, Henry Tudor, die as children. King Arthur makes his second cousin Henry Tudor, the third Duke of York, his official heir.
1975 King Arthur II dies and passes the throne to his second cousin Henry. As he only has daughters, he is concerned that his cousin William might stake a claim to the throne. He arranges a betrothal between Princess Margaret and [I still have to decide this, probably a Tudor or a distant claimant to the throne] as well as a betrothal between Princess Anne and [I still have to decide this, probably a Prince from a powerful Catholic country for an alliance]. He gives his cousin William a seat in the privy council as Lord Chancellor and appoints William's wife as a lady-in-waiting for his wife Queen Elizabeth.
1580 King Henry and Queen Elizabeth have a son, Prince John.
1590 Crown Prince John dies, leaving his mother devestated, leading her to die shortly after.
1591 King Henry VIII dies and passes the throne to his cousin William.