When King Aegon I died, it was Vhagar who ignited the funeral pyre. His death set off the first of many wars of succession, as Aenys I, son of Visenya’s younger sister Rhaenys, had been named heir instead of Visenya’s son, Maegor. Maegor was exiled, but not before claiming his father’s dragon Balerion as his own. Visenya flew off to Pentos to support her exiled son on Vhagar’s back in a rage so mighty, it was said the moon above turned red when they flew away.
Vhagar wouldn’t return to Westeros for several years, but when she did, it was with Visenya, Balerion, and her dragonrider Maegor, making their deadly claim to the Iron Throne and burning more villages, as per Game of Thrones custom. Aenys had abandoned King’s Landing in the ensuing rebellion and fled to Dragonstone, where he died of illness. The path was cleared for Visenya to place Maegor on the throne, where for good reason he would be remembered as Maegor the Cruel.
After Visenya’s death, presumed to be of natural causes, Vhagar remained unridden for nearly thirty years. Do dragons mourn? It can sometimes appear that way (look to Drogon and Rhaegal seemingly roaring with grief after witnessing Viserion’s death at the hand of The Night King.) After Balerion’s death at the respectable old age of two hundred, Vhagar was the last living original Targaryen dragon from Aegon’s Conquest and the veteran of hundreds of successful battles.
She eventually took residence in the dragon pits of King’s Landing until she met her next dragonrider, the young Laena Velaryon. Laena reveals to her daughter Rhaena in “The Princess and the Queen” that she first rode Vhagar when she was 15 years old. In House of the Dragon’s second episode, an even younger Laena expresses an interest in Vhagar’s whereabouts, suggesting that she’s always been fascinated with the big beast.
Unfortunately it seems that Vhagar was sadly destined to grieve again, as the bond she shared with Laena was not born of fire and blood, but was a relationship celebrated and beloved by all who witnessed them on their joy rides around the world.