Liv and John's relationship began as an unlikely one, as the two were on opposite sides during Beautiful Darkness. Also, Liv had an ongoing crush on Ethan. John also was with Lena, not romantically, but incited jealousy in Ethan. Liv was also a mortal, having no future with John, who is both a Caster and Incubus. However, he was able to be with Liv as he was not a full-blooded Caster or Lilum. The two fell in love while John was being questioned in Beautiful Chaos. This love changed John drastically, even causing him to transit from a Dark to Light Caster. John also had gone from a cocky bad-boy to a romantic, emotional good guy. This became apparent as he was highly emotional when he was about to make a sacrifice that later was Ethan's.
John and Liv, being on opposite sides, started off as enemies. John led Lena into a trap, leading her (Lena) straight to Abraham, Sarafine, Larkin, and Hunting in a cave. After Lena claimed herself and Larkin and Twyla died, John was trapped in the Arclight by Ridley. Meanwhile, Liv moved into the Tunnels studying ancient books.
John was found in Ridley's room playing video games by Lena. Lena and Ethan escorted John into the tunnels, meeting up with Link, Macon, and Liv. John then revealed that he was trapped in the Arclight by Ridley, and Ridley made a deal with him; if he will be her genie, she (Ridley) will do him a favor. He also revealed that he often blacked out after doing something, being told by Abraham that he was "special," confirmed by Reece to be true. It was later revealed that John would be used by Abraham to do work in the daylight, as John is invulnerable to sunlight. Liv found out more about John, and eventually fell in love with him. John also admits he fell in love with her. This love changed John drastically. He became a Light Caster after this. John also sacrificed himself after he believed it was him to die, but later turns out to be Ethan, and came as moral support.
Not much about them is said here.
Liv and John decided to head to England.