It's easy.
Triple H starts belittling KO leading to a slow turn. Sami Zayn is also feuding with Triple H/Authority at the time, and they put Sami's job on the line in a match with Triple H. Just when it looks like Sami is about to lose, Sami makes a comeback. KO hits the ring & everyone thinks he's going to save Triple H. KO shoves Sami & gives Triple H a pop up powerbomb. Then he just leaves the ring with Sami covering Triple H for the win.
This slowly leads into Sami/KO becoming a tag-team. They become tag champs a short while after.
It eventually leads to Sami Zayn turning heel on Kevin Owens