They could start with a mutual respect for each other's survival skills. For example, if the male OC is good at scavenging and Maggie is great at leading, they recognize the value in each other. This respect can then slowly turn into a deeper bond as they face more challenges together.
One idea could be that the male OC is a former enemy who has a change of heart and ends up saving Maggie from a dangerous situation. Maybe he has some unique skills, like being an expert tracker, which helps them in their fight against the walkers.
In the comics, unfortunately, Maggie meets her end. It's a sad moment for fans. The circumstances of her death add to the complexity and drama of the story.