As for why babies, and not adults, are candidates for transformation into White Walkers, this is likely because infants are easier to mold into whatever the Night King wishes.
What do the White Walkers do with the babies that Craster gives them? They turn them into more White Walkers.
All of Craster's sons that were turned into White Walkers would die when the Night King died. If they take some time to grow up, they won't be growing up. They died when he died, no matter where they are.
Since they're babies, the Night King can change them into White Walkers (his army generals) and train them as they grow up. Craster's sons were given to the White Walkers, and inturn the White Walkers protected him from wildlings and left him alone.
Craster gives his sons to the White Walkers in exchange for the safety of his keep, the security of his life and of his daughter-wives.
According to Old Nan, the Night's King may in fact be (hold on to your small clothes) a Stark! If that isn't enough, legend has it that the Night's King was not just any Stark, he was King Brandon Stark's brother—or possibly Brandon Stark himself!
Seclusion. For the next 8,000 years, the White Walkers remained in seclusion in the far North, where some fans think they spent that time in some kind of slumber or hibernation. To quote another fantasy epic: “History became legend.
The White Walker might have recognized his cowardice as surrender and therefore let him live. It is possible that the creatures wanted more than just to kill the living. They wanted subordination.
The Night King was portrayed by British-American actor Richard Brake in seasons 4 and 5 and then by Slovakian actor and stuntman Vladimir Furdik in seasons 6 to 8.
Biography. The Night's King and the Night's Queen enslaved the black brothers and performed human sacrifices. According to legend, the Night's King was originally a Lord Commander of the Night's Watch who found in the Haunted Forest a cold woman with bright blue eyes, seemingly a female White Walker.
Either way, it's all down to selection bias. The White Walkers were made from men. The vast majority of humans they encounter are men or boys, and as Game of Thrones keeps reminding us, old patterns are hard to shake off. This doesn't mean we'll never see any female White Walkers in Game of Thrones.
They can't swim, but they can't drown either
Bits of rotting flesh on bone probably aren't too buoyant in real life, either, so it's no surprise that every wight that set foot in water sank like a stone. But with no need for life-giving oxygen, you can just walk around down there!
No, the Night King is not a Targaryen.
In the books, however, the story of the Night King is slightly different. The Night King isn't the leader of the White Walkers. Instead, he's a legendary historical figure who supposedly betrayed the Night's Watch to marry a “corpse queen” and then crowned himself a king.
Walkers — devices with wheeled frames and suspended seats that let babies move around using their feet — are indeed a safety hazard. Walkers are a leading cause of injuries in babies, so health and safety experts strongly discourage their use. While in walkers, babies can roll into hot stoves, heaters, and pools.
After all the theories and speculation, we finally know what the Night King wants, an endless night. During the most recent episode of Game of Thrones, we learned that the Night King wants to erase all living memory and in order to do so, he's coming for the Three-Eyed Raven.
Based on what we've seen, the White Walkers are at least 8,000 years old: In season six, we learned that the Children of the Forest created the very first Walker as a weapon to combat the first men to arrive on Westeros. (They did so by plunging a piece of dragonglass into a man's heart.)
So, when Jon saved Commander Jeor Mormont from a Wight, using his bare hand to throw a lantern across the room—he let out a scream. He was burned by the fire; he is not fireproof.
The ultimate goal of the legendary White Walkers was the end of every living thing in existence, which they planned to achieve by killing the Three-Eyed Raven and creating an endless winter to eclipse the known world.
Exactly why The Night King insists on killing Bran is later summed up by the Three-Eyed Raven himself in season 8, episode 2, "A Knight Of The Seven Kingdoms," by stating “He wants to erase this world, and I am its memory.” Since the Three-Eyed Raven is basically a living record of mankind within the world of Game Of ...
Game of Thrones: Season 4
The baby becomes a White Walker. After being told by Morag that the baby will be a sacrifice for "the gods", Karl orders Rast to leave the baby in the woods for the White Walkers to seize him.
The White Walkers are waiting for the removal of the largest (and possibly only) obstacle to their invasion of Westeros: The Wall.
A self-professed coward with a love for books and songs, Samwell was forced by his father to abandon his birthright and join the Night's Watch so that his younger brother could become heir to Horn Hill. While at the Wall, he meets Jon Snow and quickly becomes his closest friend and ally.
But the indigenous people (a magical group known as the Children of the Forest, who look like little Jolly Green Giants) saw them as a threat. So they kidnapped one and plunged a dagger made of dragonglass into his heart, creating the very first White Walker, a race intended to protect them from the First Men.
When Tyrion announced his support of Bran being made king, he said Bran had the best stories. The world at large took that literally, and started listing every character that had better stories than Bran.