Game Of Thrones Season 6: 8 Things You Need To Know About Tower Of Joy

So much of what we know about the Tower of Joy concerns not the battle itself, but Ned's final moments with Lyanna, something he frequently remembers in the books, in particular the promise that he made her. It recurs frequently throughout A Game of Thrones, and while it initially seems that the promise was simply to take her body back to Winterfell, that hardly explains why it keeps haunting him, with a couple of the quotes pertaining to the promise particularly telling:

"He remembered Rhaegar's infant son, the red ruin of his skull, and the way the king had turned away, as he had turned away in Darry's audience hall not so long ago. He could still hear Sansa pleading, as Lyanna had pleaded once."

"'I will,' Ned promised her. That was his curse. Robert would swear undying love and forget them before evenfall, but Ned Stark kept his vows. He thought of the promises he made to Lyanna as she lay dying, and the price he'd paid to keep them."

If it were just taking her body back, then she wouldn't need to plead, and it wouldn't have such an impact on Ned. Similarly, there's hardly any price to be paid for keeping that promise; if anything, it would be expected, and the right thing to do. So there's clearly far more to the story than we've been told so far, which is why the Tower of Joy is the birthplace of so many theories, and why so many fans want to know exactly what happened there, because it could have a major bearing on the series (both books and show, regardless of other differences they may have now).