Spoiler alert: This post contains spoilers for the sixth season finale of Game of Thrones.
All hail Jon Snow, King of the North ... if that's his real name. Since the sixth season finale aired on HBO, there have been a few theories and realizations about things that author George R.R. Martin and showrunners may or may not have been hinting at all along. While some fans continued to argue the parentage of Jon Snow, Refinery29 reports that a redditor named Claire Williams was busy rewatching a key scene dozens of times to determine what King Snow's mother (Lyanna Stark) said about her son before she died. The scene shows Lyanna whispering just before the sound drops out, but according to Williams' lip-reading skills, she said, "His name is Jaehaerys."
Williams confesses that she is "not a great lip reader," but she does provide some textual evidence for why she believes Jon Snow is really Jaehaerys Targaryen. "This makes a lot of sense as a name (instead of Jon), as both previous Jaehaerys[es] to rule were considered good Kings," she writes. Williams goes on to explain that in Game of Thrones history (events that occurred before the timeline of the books and the series), Jaehaerys I was the fourth Targaryen king to sit on the Iron Throne. He was also responsible for the expansion of the Night's Watch, by suggestion from his sister-wife Alysanne. Jaehaerys II, according to Williams, "restored stability to the realm" after his father's reign (Aegon V).
Lyanna's true relationship with Rhaegar Targaryen is unclear—some believe they were in love, while others believe he took her against her will (Lyanna had been betrothed to Robert Baratheon, and her kidnapping kicked off Robert's Rebellion, which ultimately ended with Robert on the Iron Throne). What is clear is that Rhaegar spirited her away to the Tower of Joy, where she gave birth to his child, the future Jon Snow, as HBO recently confirmed in an infographic (below). "If Lyanna was in love with Rhaegar," Williams writes, "it makes sense for their son to have a Targaryen traditional name like his siblings Aegon and Rhaenys." The logic is sound, and now that the connection has been confirmed, it's hard not to side with Williams's lip reading. For the time being, let's all agree to call him J. Stark of Winterfell.