Darius Tanz

Darius Tanz (portrayed by Santiago Cabrera) is a multi-billionaire, scientist, celebrity, and inventor.

He was made Vice President by Mackenzie and, after her assassination, served as President of the United States until he resigned.

He's also the owner and CEO of Tanz Industries.

Beginnings and Season 1
Darius Tanz is a Scientist and a celebrity.

When giving a presentation as an alumnus of MIT, Darius is interrupted by Liam Cole, whom arrives late and and is notably shoeless. He meets Liam again the following day in an elevator, giving him time to explain that an asteroid was just a few months away from colliding with Earth and wiping out humanity in the process. To confirm this, Darius meets with Harris Edwards - the deputy Secretary of Defense - and is informed of the governments' plan to deflect the asteroid far enough away that it will miss Earth. However, he remains unconvinced. Impressed with Liam's intellect and computer program that detected the asteroid in the first place, he 'hires' him.

Having devised a plan of his own, he introduces Liam and Grace Barrows to RIVA - his Reusable Interplanetary Vehicle of which was initially designed to transport cargo to Mars - and intends to re-purpose it in the event of the extinction of humanity, saving 160 souls so to continue the human race. He implores Grace to assist them by providing information they could use, utilizing her position within the government, but she refuses - as does Liam. However, when the Goliath II rocket fails, Grace asks him to work with the government to deflect the asteroid and to save everyone.

Working with the Department of Defense
Darius proves problematic to work with, grinding the gears of those on the taskforce assigned to work the problem. He suggests using an electromagnetic drive attached to the gravity tractor so to get the tractor to its intended position in enough time to deflect the asteroid - which would take $2 billion (as a start) to build. Harris agrees to finance half of what he needs, but Darius fails to inform him of the 100 kilograms of enriched uranium, irritated by the 'red tape' he'd be wrapped in if he did, and demands that Grace help him get it anyway.

He sends Liam to Boston to locate Malcolm Croft's research in hopes to push the EM drive development (of which his team had already been working on for three years) further along, providing him with "walking-around money" and assigning his Chief of Security Lazlo Simms to tail him, and sets off to find the other half of his funding. Promising her a place on RIVA, he asks Catherine Adams to provide him with the other billion he needs to complete development of the EM Drive.

Grace returns as he concludes a 'meeting' with Catherine, and tells him he was right in that they couldn't trust the government, and agrees to get him the uranium. Grace then steals Harris's authorization code for transfer approval for uranium from WIPP facility in Maryland - the Waste Isolation Pilot Plant. Meanwhile, he diverts Harris' calls to his phone whilst using him to assist in further convincing Catherine in funding the other half of the project, succeeding in impersonating Harris and convincing the military operators of WIPP that the uranium transfer was indeed approved.

Liam returns with Croft and his research, and begins work on the EM Drive.

Theresa
Darius dated Theresa, Lazlo’s sister, as a teenager. He described Theresa as his biggest regret. When he was a teenager his uncle offered him wealth, but in order to gain that wealth he had to agree to break up with Theresa. He does so and later Darius greatly regrets this decision. It is revealed that his super computer “Tess” was named after her.

Grace Barrows
Grace Barrows and Darius met each other in the season premiere. It was obvious that Darius was infatuated with her shortly after they met. However, throughout the first half of the season Grace was dating Harris Edwards. Later in the season while Darius and Grace are in Russia they end up drugged and held hostage. During the time that they were captive, Darius used the record player to play Ella Fitzgerald, and shared an intimate moment of dancing with Grace. He revealed that he would miss dancing once Earth was destroyed. Darius and Grace then dance with each other to the music, also sharing their first kiss. Darius admitted that he liked her since he met her. Once he tried to kiss her he said that if she asked him to stop, he would. Grace responded by saying that what if she didn’t want to stop, leaning in to kiss Darius. After getting out of Russia, Darius' relationship with Grace became deeper than ever.

Trivia

 * The three most influential people in Darius' upbringing were his uncle, Nicolas, and his neighbors Tess and Lazlo. Combined, their names bear a striking resemblance to inventor Nikola Tesla.
 * There are some instances of the people close to Darius being referred to as "The Musketeers", and several related references are made in connection to the character. Actor Santiago Cabrera, who plays Darius, also played Aramis in the BBC period drama The Musketeers for three seasons. Salvation was the next long running television series role for the actor.
 * Darius was born in Philadelphia, making him eligible for the presidency.
 * In the first episode, Darius says that he has a photographic memory, which he describes as "a curse".