Snoke keeps Hux around so that when the time comes, he can crown Hux as Emperor and then mind control him. It gives him complete control of the Empire without putting a target on his own back.
But with the destruction of Star Killer base, Snoke decides that it's too dangerous to allow Hux to maintain his free will and so enacts the mind control early. He puts the now blank and compliant Hux under Kylo's care until they can reasonably set up his assent to the throne.
Kylo was unaware of Snoke's plan and is devastated by the state Hux is now in and decides then that he'll betray Snoke to get his general back.
+ Pre-established Kylux plz + Snoke is oblivious to how much he fucked up.
Kylo/Hux - Hux is mindcontrolled by Snoke
But with the destruction of Star Killer base, Snoke decides that it's too dangerous to allow Hux to maintain his free will and so enacts the mind control early. He puts the now blank and compliant Hux under Kylo's care until they can reasonably set up his assent to the throne.
Kylo was unaware of Snoke's plan and is devastated by the state Hux is now in and decides then that he'll betray Snoke to get his general back.
+ Pre-established Kylux plz
+ Snoke is oblivious to how much he fucked up.