Desmond

Desmond is a barkeep in New Orleans. There he met John Constantine and the two formed a relationship.

Biography
In 2018, Desmond met John Constantine at a bar and formed a relationship.

Sometime after, hunted by a powerful demon Neron Constantine asks Desmond to leave town. But he didn't listen and made a deal to bind his soul to Neron's to save John's live. Constantine finds out about it when in attempt to send Neron to Hell he has to send Dez there as well.

New timeline
Several months later, when Constantine joined the Legends, they travel to New Orleans during a mission where John is confronted with Marie Laveau - great-great-grandmother of Desmond.

Laveau pressures Constantine to save "the last of [her] line" and he returned to the night they met with Charlie and had her prevent the two from meeting.

However, Desmond and Constantine would meet again days later, leading to the assumption that their meeting is a fixed point in time, meaning they were supposed to meet and this event can't be changed.

Constantine then decides to travel back and break up with Desmond before he could fall for John, lying to Dez he simply used a love spell on him and what they had wasn't real. Desmond claimed what they had was real before leaving, which causes the whole time line to change.