Final answer:
Tiberius set precedents including imposing strict regulations on public actors and proposing a court system for senatorial corruption, which were seen as challenges to the Senate's power. His brother Gaius further strained senatorial relationships with his radical reforms, leading to his downfall and the Senate taking drastic measures against him.
Step-by-step explanation:
Tiberius set several precedents that were met with varying reactions from the senators. As emperor, he continued some of his predecessor Augustus's policies, but also made significant changes. He expanded the powers of the Princeps, often overshadowing the Senate, which led to political tensions.
One of Tiberius's precedents involved reining in the histriones, or actors, who were causing public disorder and commanding too much influence over the people, leading to sedition against the state. The Senate's reaction was mixed - some were in favor of Tiberius's strict regulations, which included expelling the actors from Italy, while others viewed his measures as an overextension of imperial power.
Another precedent by Tiberius was his response to accusations of corruption and the establishment of a court system, which threatened the Senate's autonomy. This move caused great consternation among senators, as it gave Tiberius the ability to exert more direct control over senatorial conduct.
Gaius, his brother, also pushed for reforms that challenged senatorial power, including proposing new colonies for land redistribution and free grain for the poor. His election as tribune for two consecutive years, violating Roman tradition, and his proposal for a court to try senators for corruption were particularly disturbing for the Senate, which eventually culminated in his death and the massacre of his supporters.