As thorough as the Marvel Cinematic Universe is, I feel as though there are still some overlooked characters. Now, this may be intentional. They may return to address some of these characters later, but for now, all that you're about to read is simply conjecture.
One of these such overlooked characters is Obadiah Stane, also known as Iron Monger.
(Warning for spoilers from Iron Man and Captain America: The Winter Soldier.)
We all know Obadiah from the first movie in the Iron Man trilogy. He had been Tony's mentor and friend, as well as Howard Stark's friend, before his true nature was revealed. He turned on Tony in an unexpected turn of events, which ended in Stane's death at the end of the movie.
Aside from greed, there doesn't seem to be a clear motive for Obadiah's actions. Greed is a strong motivation, but I don't believe it's the only one. Or enough motivation to attempt to murder the son of a former friend. However, I believe greed was not his only motive. I also believe that this series of events was a long time in coming. The deaths of Howard and Maria Stark were mysterious at best. They were dead before their time in a tragic car accident. Then, in Captain America: The Winter Soldier, Zola practically admits to Steve and Natasha that Howard and Maria were murdered by the Winter Soldier. This means that Hydra had an interest in arranging their deaths. I believe they had multiple reasons for this and gained several things from it.
After Howard's death, Obadiah took over Stark Industries. I think this is exactly what Hydra planned. My theory is that Obadiah was part of Hydra even while Howard was alive. It is possible that he had been Howard's friend at first, but was recruited by Hydra sometime later. Once they had a man in the place that they wanted, they could rid themselves of Howard. It would be a smart move for Hydra. They would gain control of one of the largest weapons manufacturing companies in existence. Obadiah admits to Tony in the movie that they were dealing under the table. Zola tells Steve Rogers that Hydra manufactures chaos and war. The double dealing would have been one way this could have been done.
Hyrda has permeated almost every one of the Marvel movies thus far, to make no mention of Agents of Shield. Their actions have been well hidden and under the table. It wouldn't be surprising if they were behind more than we already know about. All this is mere speculation, however, until the MCU allows us deeper insight into Hydra's actions.
