"Billions" is once again spelled with a "B."

B as in Bobby Axelrod or "Axe" to his friends (and definitely not the body spray). The former billionaire CEO of Axe Capital hedge funds (played by "Homeland" star Damian Lewis) returns for the seventh and final "Billions" season (streaming Friday on Paramount+/Showtime, airing 8 EDT/PDT Sunday on Showtime).

The cool, calculating heart of "Billions" ended his onscreen run after finally losing his five-season alpha dog feud with long-running legal nemesis New York State Attorney General Chuck Rhoades (Paul Giamatti). In the 2021 Season 5 finale, Axe jetted (on his $600 million private plane, naturally) to Switzerland, safe from extradition for his business crimes, rather than surrender to Rhoades.

But after a season's absence, Axe has battled back for the drama's final run. Here are "Billions" of reasons why.

Why did Damian Lewis leave 'Billions' and then return?

Lewis, a British Shakespearean actor, started discussing a potential exit from the show years before Axe's departure, expressing a desire to spend more time with his England-based family. In April 2021, Lewis's actress wife Helen McCrory ("Harry Potter," "Peaky Blinders") died at age 52 from cancer.

Six months later, Lewis said his official goodbye on Twitter, writing, "I'll miss the 'Billions' family. Yep, some jobs are more than just a job…. Love."

Onscreen, Axe told rising rival Mike Prince (Corey Stoll), who was key to his ouster but also allowed him to escape the country, “So this is what it's like to lose."

But show creators Brian Koppelman, David Levien and Andrew Ross Sorkin always kept the parachute door open for a return, however improbable. "The goodbyes on 'Billions' and the hellos on 'Billions' are never permanent; nothing is etched in stone," Koppelman told EW.

In February, Lewis announced that "Bobby's back" for Season 7 on "The Late Show With Stephen Colbert."

Why does Bobby Axelrod return to 'Billions'? And how long does he stay?

Season 7 will focus on stopping Prince, the man who assumed Axe's throne. Literally, Prince portentously sat in Axe's revered office chair after buying Axe Capital from his fleeing rival.

The charming Prince showed effortless business acumen and cold-steel political ambitions in Season 6, serving in Axe's usual role as Rhoades' main adversary. Prince is so good that his seemingly unstoppable rise and materializing Season 7 presidential dreams freak out the people who know him best. They put aside their own bitter differences to rally and thwart him.

Former Axe confidante Wendy Rhoades (Maggie Siff), past loyal Axe lieutenant Mike "Wags" Wagner (David Costabile) and rightfully embittered Axe protege Taylor Mason (Asia Kate Dillon) are all in on the scheme of summoning the near-mythical Axe to return to lead the battle. For Axe, there is the added incentive of taking back the kingdom from his conquerer. They meet outside England's Tower of London to continue the British monarchy succession theme.

“I'm back now, and I'm wide awake,” Axe says later.

How Axe makes the return, despite the overwhelming legal problems he faced in Season 5, and what he's been up to while on the run will be explored in later episodes. His role increases through the Oct. 27 "Billions" finale, which promises to be a final showdown.

Is this the end of 'Billions'? Will there be spinoffs?

"Billions" is winding up its hit seven-season story of the uber-rich seduced and corrupted by money. But Showtime has made a serious franchise investment, announcing a slew of spinoffs in February with working titles.

These include "Billions: Miami" which Koppelman and Levien were already writing when the shows were announced, set in the world of private aviation amid the wealth, nightlife, contraband and the cryptocurrency of Miami.

Across the pond, there are plans for "Billions: London," which focuses on the work of U.K. finance. For the aspiring crowd, there's a show tentatively called "Millions," featuring 30-something financial mogul wannabes.

Finally, focusing on the uber-ubers, there's "Trillions," based on fictional stories of the world's richest people and the titan of industry battles between them.

There's no word on starting dates, casting, or whether any of the "Billions" cast will take part in the new franchises.