It was Prince Rhaegar’s young son Aegon whose head was dashed against the wall by the Lion of Lannister’s brave men.
In the interest of guarding against epistemic closure I present to you maybe the first post I’ve ever read that proceeds under the assumption that Aegon Targaryen is exactly who he is alleged to be. I don’t buy it at all for reasons I’ve discussed at length, but there you have it.
Extra points for the subtheory that the baby slain in Aegon’s place was, somehow, Ashara Dayne’s. I feel like that guard in History of the World Part I who asks if people know the penalty for a slave who strikes his master and a guy shouts out “They shove a living snake up your ass”: “No, but that’s very creative.”