GTA 6 integrates the relationship between Lucia and Jason into optional activities. When playing as Jason, players can text Lucia to arrange a meetup; the pair may then go for a walk, work out, or rob a store together. These interactions must be discovered by players and are not part of the mandatory fixed storyline.
Rob Nelson, co-head of development at Rockstar, told Bloomberg journalist Jason Schreier that the team had concerns about how to handle the couple's relationship. However, since the game centers on a pair of partners, the team had to commit seriously to this premise.
After arranging a meetup via text, Jason and Lucia might take a stroll in the park, hold hands, and discuss their pasts. They can also head to the gym to exercise individually before jointly robbing a store and evading the police; throughout this process, the two continue to flirt and chat casually.