BRETT DALTON’S EVER-SHIFTING GRANT WARD
The biggest shift in the show (and indeed one of the biggest shifts in superhero television) was Grant Ward’s heel turn from stoic SHIELD agent good guy to bad guy HYDRA minion. While the former hero turned anti-villain tore the team apart from the inside out, that turn ultimately was responsible for several of the major shifts within the show. Without Ward attempting to do good Daisy would never have ended up in the temple and become Quake, Coulson would probably trust people a lot easier, and the entire team would have had a lot less to do with the Inhumans and their struggle for rights.
That’s ultimately how Ward’s story ended; after becoming the head of HYDRA he literally became the embodiment of evil after Coulson killed him and failed to stop Hive from heading back to earth. Hive ultimately resulted in the death of Lincoln Campbell, Daisy’s boyfriend, who sacrificed himself to save the team. That ultimately drove Daisy away from SHIELD where she used her spy training to survive. That brought her face to face with Ghost Rider. Basically #ItsAllConnected back to Grant Ward.
As for Ward, he finally found redemption in an alternate reality within the Framework as a double agent working for SHIELD and raised by Victoria Hand. He ultimately sacrificed himself to save the team, keeping the signal going so they could escape Aida’s reality.