Jon Snow and Daenerys TargaryenTwitter/Official Game of Thrones page

Game of Thrones season eight is going to premiere in April and it will show one final battle where Jon Snow and Daenerys Targaryen will fight the Night King. In order to defeat the greatest enemy, the Targaryens will be needing something more than the support of armies and two living Dragons — may be the Lord of Light can help them?

Before we go into the detail about Jon Snow and Daenerys Targaryen offering some human to save all the Seven Kingdoms, let us dwell into the history of Jon and Dany, and what makes their sacrifice the one which the Lord of Light might be seeking.

Jon Snow's part:

In the previous seasons of GoT, we were shown the tragic history of Jon Snow's real parents. His mother, Lyanna, died shortly after giving birth to him but not before asking her brother, Ned Stark, to take the child and protect him as his own son. She asked Ned to "promise" her that he will be taking good care of the child.

Several fans have pointed out that the word "promise" can be taken into account and could be read as The Prince That Was Promised.

At the same time, in the published books and the subsequent series, we know that the Red Priestess once said, "I pray for a glimpse of Azor Ahai, and R'hllor shows me only Snow."

Melisandre will resurrect Jon Snow in the latest season.Facebook/Game of Thrones

Over the years, many believed that "Snow" in this dialogue refers to Jon Snow who was considered  the promised prince.

Daenerys Targaryen's part:

When it comes to Daenerys, things are a-la her partner Jon Snow. She was born on Dragonstone among the salty sea. In the very first season, she woke dragons from the stone when she placed the eggs into her dead husband Khal Drogo's funeral pyre. Her exit from the fire could be considered her resurrection by the fire. All this happened when a red comet, a "bleeding star" appeared in the sky.

In the book, Aemon Targaryen tells Samwell Tarly that as per his predictions, Dany is the Prince Was Promised.

"Dragons are neither male nor female... but now one and now the other, as changeable as flame," Aemon tells Samwell. "The language misled us all for a thousand years. Daenerys is the one, born amidst salt and smoke."

Jon Snow and Daenerys' human sacrifice:

We all know that Jon and Dany both have some important roles to play in the story. Now many believe that they will be the ones to have some human sacrifice in order to defeat the Night King.

Where did we first see the human sacrifice in Game of Thrones? Well, if you remember, back in Game of Thrones season five, after Ramsay Bolton and his men infiltrated Stannis Baratheon's camp, and destroy all supplies and horses, the later was instructed by Melisandre to sacrifice his daughter Shireen to ensure the victory. Although, the end did not come in Stannis' favor who died shortly after burning his daughter alive.

Well, in order to please the Lord of Light, Jon Snow and Daenerys Targaryen can be asked by Melisandre to offer some human to ensure their victory against the Night King. Chances are they can donate their own child to Night King. If they do it, then Jon and Daenerys' child could become Azor Ahai — The Prince Who Was Promised or the Last Hero.