Britney Spears sparked romance rumors with a mystery man named Brandon Walker when she returned from a recent getaway in Cabo, but what's really going on between them? "Brandon Walker is a bodyguard," a source exclusively tells Us Weekly. "They are not romantically involved." Spears, 44, was spotted arriving at LAX with Walker, who is also a fitness influencer, on Monday, December 15, following her birthday celebration in Mexico, as seen in photos published by Page Six.