Henry and Richard were born rivals

Henry and Richard were born rivals. For a start, they were almost exactly the same age. Richard was born at Bordeaux, in Gascony, on 6 January 1367; Henry was born at Bolingbroke, in Lincolnshire, just three months later. Although they would not have met until they were five or six, they were regarded as a pair, on account of them both being the king’s grandchildren and the same age. Moreover, they were the only two royal children of this age; the next eldest, Roger Mortimer, was seven years younger. … they were the heirs of the two most important dynasties in England. More than a hundred years earlier, King Henry III had two sons The elder had been crowned Edward I. The younger, Edmund, has been endowed with a massive inheritance in the north of England, centred on Lancaster which gave rise to his title of earl of Lancaster.

I. Mortimer, The fears of Henry IV (2007), 19