3. John responded to being summoned by threatening to excommunicate everyone at the Synod, and started a riot by offering a bounty for Otto’s head
John’s reaction to the summons was typically measured and proportionate. He wrote back to his Lateran Council to inform them he would not be attending, thundering that the Synod was illegal and threatening to excommunicate everyone present. And then he put down his quill (we know it was his quill as the letter’s Latin grammar is absolutely terrible), jumped on his horse, and went off hunting again. But he also found time to have a bit of a think about the future, and decided to offer a huge sum of money in exchange for Otto’s head on a plate.
Otto, as a German, was very unpopular in Rome, and people were so desperate to collect the bounty on his head that a riot was soon underway. Otto quashed the rebellion with brute strength, making him even more unpopular. Poor old Leo was also widely-despised just because Otto had backed him as Pope, and was left on very shaky ground in the aftermath. It says something of John’s ridiculous character that he didn’t simply do a bolter with the Vatican wealth and settle in a neutral land, but instead decided to fight the older, wiser, and much more powerful Otto.