Possible Clues:

• Pope's name
• Name chosen thus far by 12 popes
• There have been twelve Popes with this name
• Pope with an apt-sounding name
• Pope with an appropriate-sounding name
• WW two Pope (XII)
• Name used by 12 popes
• Six before Francis
• Apt papal moniker
• Only name used by three 20th-century popes