We've already discussed the possibility that Jon and Dany will have a child together.
And it seems that theory's spread pretty far around the internet, because it's hard to open a Reddit thread these days without seeing someone worrying about the consequences of J + D = b(oat) b(aby).
So let's assume it's not just a possibility but a certainty. For the sake of argument.
Here's a collection of some of the more serious concerns around this (not-so) shocking future twist, a twist that'll almost certainly happen in the lead up to an ending George RR Martin has described as 'bittersweet.'
1. Jon and Dany's baby could be the next Mad King
This is the big one that's got Game Of Thrones geeks hot under the collar. In the world of Westeros, incest is frowned upon but it happens. Especially amongst Targaryens, who (like the Ptolemaic pharaohs) practice incest to keep the bloodline pure.
But every now and then, sleeping with your aunt / cousin / brother / mother in Westeros throws up an utterly evil or mad family member.
We've seen it in the Mad King, and more recently with Dany's brother Viserys (remember him? The one who did the ice bucket challenge with a pot of molten gold?) and, actually, with Joffrey (who wasn't a Targaryen but was the product of incest, and who was a poisonous little sadist.
Incest babies have a propensity for evil in Westeros.
Fans are worried that Jon and Dany's could have the same traits as Joffrey, leading to an ironic end to the series – in keeping with the show's 'the more things change, the more they stay the same' vibe. Jon and Dany will rule wisely, but their successor will basically mess everything up all over again.
Still, there are reasons to be cheerful. Firstly there's the actual science that incest babies aren't actually all dangerous sociopaths (not that GoT particularly cares about science). But, mainly there's the fact Jon's got Stark blood (basically the good-est and most honourable-est blood around) which should hopefully cancel out any Targaryen nastiness.
Also, Daenerys is pretty determined to "break the wheel" of good-monarch-bad-monarch history, so would she put her child on the throne at all, whether he or she was pleasant or not?
2. Jon and Dany's baby could be killed by Tyrion
Attentive fans have noticed something interesting about the moment in season four's 'The Mountain And The Viper' where Tyrion lists all the different terms for killing someone.
The list is "Matricide, patricide, infanticide, suicide," and some fans believe all of these terms will eventually apply to Tyrion.
He killed his mother when he was born, then killed his father with a crossbow as an adult. Some fans feel this is the beginning of a pattern, and that Tyrion will kill a baby next, before taking his own life because of the subsequent guilt.
And this has arguably been foreshadowed – remember that look Tyrion gave Jon and Dany before the boatsex?
If he's unhappy about them getting together, imagine how he'll feel if a baby comes out of the union.
And before you say, "That's a ludicrously tenuous argument, why do I even come to this stupid site any more?" recall that George RR Martin always reveals his twists in three stages: the first invisible to all but the sharpest of readers, the second so that the general cleverclogs can spot it, and the third so that even an idiot can't miss it. Think about all the invisible foreshadowing in that Littlefinger quote about "people die at their dinner tables…"
3. Jon and Dany's baby could make them vulnerable
Dany's been told she can never have children. Jon swore an oath that he would never take a wife, or have a family. Both weren't especially happy about those situations when they realised the implications of them.
So, faced with the possibility of having a baby – something they never thought they'd be able to do – they're probably going to react in a fairly emotional way. And if there's one thing we've learned from fiction, emotions make you vulnerable, and potentially weak, especially during times of war.
Will Jon go all over-protective of his child? Will Dany go on the offensive to protect her family? Either strategy could lead to mistakes and fatal consequences.
Could Jon and Dany's baby prove to be their achilles heel?
Fans are worried that the Night King will use Jon Jr against his parents, which leads us to our next concern...
4. Jon and Dany's baby could be what the Night King really wants
Just why is the Night King so obsessed with coming to Westeros anyway? Sure, he could just be a maniacal evil dude who wants to rule the super-cold world, but George RR Martin doesn't really work like that. If the Night King's just a generic villain, it'll be disappointing, and not in keeping with the world Martin's established at all.
No, NK will probably have a – subtly foreshadowed – reason for heading south, and some fans are convinced it's linked to Jon and Dany's baby. After all, he's let Jon live more times than he's tried to kill him – potentially so he could survive… to make a boat baby!
Introduction scenes are pretty important in fiction, and what was the Night King doing when we first met him? Why, turning a baby into a White Walker, of course! Perhaps he's doing this as practice before he meets the ultimate GoT baby, the child of ice and fire...
5. Jon and Dany's baby could be Nissa Nissa
The Azor Ahai prophecy requires a hero to plunge a sword into the heart of the hero's true love, to create Lightbringer, the sword that will save the world.
We're still not sure who or what Azor Ahai will be, but Jon and Dany are the two people who have been connected to the prophecy most on the show.
So, whichever one of them it is, they're likely to consider their child to be their true love (the love between a child and its parent is pretty unconditional, after all) which means that we could see a scene in Game Of Thrones season eight featuring one of the show's two main leads killing a baby to save the world.
Which would bring new meaning to the word 'bittersweet.'