What I don't really get is what was the point of the Children of the FOrest (or whatever they're called) making the white walkers? Was it punishment against men? Did they expect them to become their soldiers and it had unintended consequences? Because clearly now they're against the white walkers. Theories?
Just my theory. There were a bunch of Child of the Forests who were hooked up to Weirwood trees just like the guy teaching Bran. These were the 'old gods' that people worship (Maybe masters of ice magic? Their duty was to witness and preserve things). They create the white walkers as their personal army to help the rest of the Children during the war. War goes on, the white walkers help but all they do is slow the men during the winter in the far north--during the summers and spring men fuck up the children every year, to the point where the war, despite the walkers, is a stale mate (Essentially the walkers only stop the final blow, they don't really let the Children win). This lasts a thousand years, until finally the men and children relent and make peace. (Remember, the men were steadily winning for a long time, even after the children went scorched earth and blew up a big chunk of land. Then something happened which made the men want peace--probably the stale mate from the white walkers.)
Except
oneof these old gods won't accept it, too many children have died, fuck the men--it becomes the Great Other. There is a civil war of sorts among the Children, that's why they slowly disappear. But the children force the "Great Other" to retreat, not before him and the white walkers fuck up the rest of the old gods (Robbing the children of ice magic). The great other realizes his weakness is the summers, and so collects his magic for thousands of years and slowly begins to push the seasons out of balance.
Children are powerless to stop this, or don't even understand it themselves as its more of a thing the 'gods' are doing (And most of the other old gods are dead from the civil war). Long night comes, white walkers return. Children join the first men to fight them because the rogue old god, the Great Other has gone nuts. During this time though, the children have shared some (Fire) magic with the humans (The only type they still have)--humans develop children fire magic the same way they did technology (Constantly improving it). They mix it with blood magic, and Azor Azhai is born. He beats back the walkers, and after, humans who were able to learn the magic the Children taught them raised the wall. But the fire magic couldn't make it all the way up north, and thus the Great Other retreated to collect his power again.
Then after the nights watch is formed, a female White Walker goes and fucks the lord Commander. It was meant as a way to subvert the nights watch to allow the great other a new shot, but it accidently produced children--children who survived the Commander being killed. Children who had the powers of ice magic (Warging/green seeing)...That's how you get Starks. A few of these Wargs/Seers are extremely powerful, and can hook themselves up to trees to become like the Old Gods. Bran is the most powerful. That's the key to finally defeated the Great Other, the humans/children now have access to ice magic again, the old gods magic (Melisandra says the guy on the tree is the face of the enemy--maybe she misinterpreted the vision, he is the face of ice magic, so the same magic the Great Other uses, but not the enemy)--ice and fire working together.