What Khal Drogo's Death meant to the Plot.
Drogo, more commonly known as Khal Drogo, cheiftan of the Dorthraki people, though was a powerful warrior was killed off during Season One. How he died was rather disappointing too, from infection from a small cut to his arm, which is no way for a Warlord to die. Well, if we want to get technical, after that he was brought back to life (in a coma) by a witch, but was then killed for mercy by Daenerys. However, even though he was one of the most dangerous and merciless people in the whole of the Seven Kingdoms, he learnt compassion... Imagine if all of the Dorthraki people learnt to feel compassion and love, their kind would not have been only unstoppable, but could of ruled without being cruel. The thing is, what would of happened if Drogo didn't die? What would be different? Well lets take a look...
If Khal Drogo didn't die, there wouldn't of been a need to cremate him in fire, so... Daenerys Targaryen wouldn't of stepped into the flames with her Dragon eggs, so she might of never of became The Mother of Dragons. Though she did realise this before, so she might have hatched them in a different method but yeah, theoretically, he had to die in that regard. Obviously, Daenerys uses her Dragon, Drogon (named after Drogo) to trick the trader into selling her the Unsullied Army. On the other hand, if she was still with Drogo, she would still be their Khalessi, and they would of sailed across the Narrow Sea together to take the Iron Throne with their horse-riding Dorthraki army.
Another thing, back in King's Landing, Robert Baratheon who was still king when Daenerys was pregnant, wanted her dead. Cause obviously, since the beginning of his reign, he wanted all of the Targaryens dead cause they were the reason he lost the love of his life Lyanna Stark, the reason the whole rebellion started. He wasn't so bothered about killing her when she wasn't pregnant, cause he knew of her whereabouts and knew she wasn't a threat. However, knowing she was going to give birth to a Dorthraki Warlord's son and future Khal with Targaryen blood, he knew he had to kill the baby, and Daenerys. So, if Khal Drogo didn't die, perhaps his partner and son would have perished instead, and that is a terrible burden, which Daenerys now carries.