On a recent Sunday in Rome, Pope Francis channeled his inner Hell’s Angel and mingled among thousands of leather-clad Harley Davidson bikers who had descended on the Holy See. They were there for a papal blessing as part of the 110-year anniversary celebrations for the legendary American motorcycle manufacturer. Saint Peter’s square was jammed with priests, nuns, tourists, and extremely nervous security officials who seemingly had no idea what the pontiff might do next.

“He is unpredictable,” a concerned security guard told The Daily Beast, eyeing the giant monitors set up in the square with one eyebrow raised as the Popemobile pulled up to the papal platform at the end of mass. “Is he coming back out? We’ve already opened the barriers to start clearing the square,” the guard barked into his radio. “What am I supposed to do now?”

The pope then hopped into the back of his open jeep and the driver wheeled him around the remaining secure section to the sheer joy of those who had stayed until the bitter end of the mass. His security detail, however, was visibly frustrated—the charming spontaneity that has made Francis so popular with the people is an increasing concern for those whose job it is to protect him. “We all have to rewrite the rules to account for his unpredictability,” Father Thomas Rosica, a Vatican spokesman, said shortly after he was elected. “But thank God for a pope who keeps us guessing.”

The papal unpredictability may be manageable in Rome, where his security is a well-oiled machine even with an impromptu pontiff. But those close to this pope are worried about how to protect him during his upcoming trip to Brazil, where up to a million people have been involved in increasingly violent protests in cities across the country. Francis is scheduled to touch down in Rio de Janeiro on July 22 to preside over six days of World Youth Day events, a sort of Woodstock-style festival for young Catholics. While Pope Francis is not expected to be the target of protests, the cost of his visit is touching a nerve, especially given the fact that the protests in Brazil started because of a 20-cent increase to a transport fare.

Francis’s trip was a costly endeavor for the Brazilians even before the unrest began. Brazil is the first nation to welcome the first Latin American pope on the first trip of his papacy—a combination of factors that will draw massive crowds. Brazil will deploy up to 12,000 troops to secure the areas where the pope will greet up to 3 million Catholic youth who are expected to attend the event. He will be guarded 24 hours a day by dozens of highly trained officers from Brazil’s elite national-security forces, using four state helicopters and armored cars to shuttle him between events. More than 40,000 regular police from a force already stretched by the protests have been allocated to mind the event.

The pricey papal visit is one of a number of high-cost events Brazilians are angry about. The protests began over a series of taxes and cost increases levied to help cover costs of the World Cup next year and the Olympics in Rio in 2016. The Brazilian bishops conference has supported the protests, declaring “solidarity and support to these demonstrations, as long as they are peaceful, which have taken to the streets persons of all ages, especially the youth.”

Brazilian bishops have downplayed security issues and concerns that violent protesters will infiltrate World Youth Day, with one top-ranking official even likening the protests to the spirit of that event. Orani João Tempesta, archbishop of Rio de Janeiro, issued a statement in which he compared the two movements: “In some ways the protests are similar to the spirit of WYD—the desire to work together for a new world, for a new life, a new society.” He told a local Rio newspaper that he wasn’t concerned about safety because event security has been highly scrutinized. “I think that there will not be any safety issues, whether for the pope or for those in attendance as we are studying everything down to the smallest details, to all of the minutiae,” he said.

But that may not take into account a capricious pope who does not necessarily play by the established rules. An official with the Vatican told The Daily Beast that the World Youth Day events are choreographed with little wiggle room to keep everything on schedule. But he admitted that keeping Pope Francis from reaching out to his followers is a huge challenge. “This is the most unpredictable pope we’ve ever had,” he said. That’s probably also why he’s also the most popular.