Meeting Charles Xavier and Erik Lehnsherr
When Jean Grey's mutant abilities started to manifest, John and Elaine Grey invited Charles Xavier and Erik Lehnsherr to their home in order to discuss the appropriate course of action to take regarding their daughter's future. When presented with the option of having Jean attend Xavier's School for Gifted Youngsters, John instead asked how her mutation would be treated, likening it to an illness that needed to be cured. John's words angered Lehnsherr, causing Xavier to ask if he and Lehnsherr could speak to Jean in private.
In the revised timeline, John Grey was wounded in a car crash inadvertently caused by Jean Grey in 1975, which claimed Elaine's life. John resented Jean as a result, and when visited by Charles Xavier in the hospital, gave him custody of his daughter. Xavier informed Jean that John had died in order to shield her from the trauma of being abandoned by him, and took her to Xavier's School for Gifted Youngsters. Following his recovery, John returned home, where he mourned his wife's death, placing photos of her around his house, although he chose not to hang any of Jean due to his resentment.
Following Jean's absorption of the Phoenix Force in 1992, Jean's psychic abilities were significantly enhanced, and she heard John's thoughts. Realizing John was alive, Jean fled the X-Mansion and returned home, reuniting with her father. However, Jean realized there were no photos of her in the house and inquired as to why John never looked for her following the car crash. John explained that Jean took the woman he loved away from him, and after being informed by Jean that she could read minds, intentionally recalled the car crash and ensuing memories for her to experience. He began to notice tremors and demanded that Jean stop whatever she was doing, although Jean notified him that it wasn't caused by her as she rendered him unconscious.
As he came to, he was being surrounded by police officers before being dismissed by Vuk and Jones, shape-shifting aliens who were posing as FBI agents. Vuk asked John to tell him what he knew about Jean; when John asked for a lawyer instead, Vuk tortured him for information before killing him.