Dr Pepper is now as popular as Pepsi. It’s still shrouded in mystery.

“Prune juice.” “Barbecued water.” “Elixir of the gods.”

Those are just some of the phrases used to describe Dr Pepper, the un-pin-downable soda brand whose secret recipe is said to include 23 flavors. This week, we learned that the purplish-red canned beverage (see, even its label contains an enigma!) had joined Pepsi to become the nation’s second-best-selling soda, behind category-dominating Coke, according to trade publication Beverage Digest. (Dr Pepper is technically a smidgen ahead, but it’s essentially a tie.)

That news might have surprised even some of Dr Pepper’s most ardent fans, many of whom revel in the kind of weird aura that surrounds their beloved, inscrutable drink. But Pepsi’s fortunes have declined, and the good doctor’s have risen, and now each brand represents 8.3 percent of the soda market. (Coke is ahead comfortably with 19.2 percent.)

The drink’s story started in 1885 at Morrison’s Old Corner Drug Store in Waco, Tex. There, pharmacist Charles Alderton was supposedly inspired by the intermingled scent of the various fruit syrups used to flavor sodas, and so he created the blend to achieve the concoction’s now-iconic flavor.

More than a century later, among the shelves of bland corporate products, Dr Pepper has always felt like a freaky anomaly, a brand shrouded in mystery. Here are some of the questions surrounding it:

Who was Dr. Pepper?

We don’t, in fact, know whether there was an actual medical doctor in the house who served as the drink’s namesake; history is unclear on this point. According to the Dr Pepper Museum in Waco (yes, such an attraction exists), researchers have collected more than a dozen stories about the name’s origin. Several fanciful ones involve a Virginia pharmacist named Dr. Charles Pepper, for whom the owner of Morrison’s drugstore once worked. The younger man was said to have fallen in love with the boss’s daughter, and persuaded Alderton to name the drink in her honor. More likely, though, is the common practice at the time to add “Dr. So-and-so” to the labels of products said to have health benefits, according to the myth busters at Snopes.com.

What are Dr Pepper’s 23 flavors?

Although the company has, over the years, boasted about the 23 flavors that make up the taste, Dr Pepper has been extremely cagey on this point. Watch how carefully Adrian Sepcic, the company’s senior manager for research and development, describes it as “a blend of fruit flavors and extracts.” Dr Pepper Canada even pokes fun at the secrecy surrounding it, with a feature on its website promising to reveal the list, only inviting users on an endless scroll.

The exact recipe is cloaked in mystery: According to Snopes, the master formula for Dr Pepper is divided in two and kept in separate bank vaults in Dallas. (Can someone please make Dr Pepper the subject of the next feature film treatment, a la Pop Tarts in “Unfrosted” or Cheetos in “Flamin’ Hot”?) Amateur soda sommeliers have suggested the list is amaretto, almond, blackberry, black licorice, caramel, carrot, clove, cherry, cola, ginger, juniper, lemon, molasses, nutmeg, orange, prune, plum, pepper, root beer, rum, raspberry, tomato and vanilla.

Is Dr Pepper made with prune juice?

No, the company has stated unequivocally that it does not contain prune juice. The myth has persisted, even though its origins are as murky as a Dr Pepper float. The folks behind the Dr Pepper Museum blame none other than Bob Hope: “We believe the rumor was started by a comment by Bob Hope when he was visiting the Waco area at one time,” the museum’s website states. It doesn’t say what, exactly, the joke was, but some people have suggested it was something along the lines that if Dr Pepper did contain prune juice, he would know where its fans were at 10, 2, and 4 p.m., echoing the brand’s long-running tag line suggesting people drink it for an afternoon boost. Har-har.

But wait! It’s possible that it contains prune flavor, just not juice. And some internet sleuths have theories that one of the fruit flavors it contains is plum, which is, of course, a prune in its undried form. So its possible that tasters picking up on notes of prunes might be on to something.

What happened to the period in Dr Pepper?

Medical doctors use a period after the abbreviation, but let’s recall that Dr Pepper is not a practicing physician. The company says it dropped the period in the 1950s, a move many people suspect was to improve its legibility on labeling and in advertisements.

Who owns Dr Pepper?

The brand eventually became part of the Dr Pepper/Seven Up Bottling Group, which was purchased and spun off as the Dr Pepper Snapple Group. Coffeemaker Keurig ultimately bought it, and it is now part of the Keurig Dr Pepper umbrella.

Can Dr Pepper get any weirder?

Heck yeah. Regular Dr Pepper is just the kooky start. The company long advertised drinking the stuff hot for a winter warmer. (I actually tried it, and it was pretty good.) And a recent viral trend involves dumping pickles into the drink.

At times, the company has leaned into its own weirdness. For a while, it adopted the moniker of the “world’s most misunderstood soda,” including in this unhinged TV ad featuring the great Carol Kane. It also promoted itself as the “most original” in its category. And even if it’s now gone mainstream, for its fans, it will always be the drink dispenser’s delicious oddball.