He was not of the bishop's flock

But the tyrant thought the bishop would be a good choice for a particular diplomatic mission.

When the bishop arrived at his assigned destination, he was greeted with reverent enthusiasm by people at the very highest levels. The bishop returned the favor by giving strong affirmation to his host and, consistent with his mission and his conscience, passed on a message of peace and kindness (while still upholding truth).

After the bishop returned from his mission, the tyrant went into a rage, threw the bishop into prison, and deprived him of food and water.

John, the first Bishop of Rome to use that name, died there on this very day in the year 526.