A mysteriously broody character such as Buffy the Vampire Slayer and Angel's good guy vamp Angel is bound to have a few skeletons rattling around in his dark (no, sunlight, please) closet.

Angel wasn't your typical hero-- he was a vampire with a soul, after all. He wasn't your typical TV boyfriend, either-- he went from creepy stalker to sacrificing his happiness for Buffy's future. Given his various unique storylines and dark history, the character built up a lot of secrets during his time in the Buffyverse.

How much of Angel's rivalry with Buffy's buddy Xander was real? (Turns out, a lot, actually.) How did David Boreanaz stumble into the role that would launch his acting career and who lost out on the part along the way? (Surprise, it's another popular Whedonverse presence.) Also, who would Sarah Michelle Gellar choose in the eternal boyfriend debate of Angel vs. Spike? (Get your boxing gloves ready.)

From Angel's real soulmateto love scene prank wars and getting nude on set, here are the 15 Things You Didn't Know About Buffy the Vampire Slayer's Angel.

The Angel/Xander Rivalry Wasn't Only On-Screen

Watching a 245ish-year-old vampire reduced to a petty, jealous boyfriend was part of the fun of the onscreen rivalry between Buffy's love and her best friend, Xander Harris. Xander never actually got his shot with Buffy, but that didn't stop Angel from getting in a jab or two whenever he had the chance.

Sadly, this onscreen drama spilled over into reality.

When the cast and crew gathered together for their 20th-anniversary reunion, David Boreanaz did all he could to be kept apart from Xander actor Nicholas Brendon.

According to Brendon, Boreanaz refused to participate in the shoot with Brendon. During the Wales Comic Con in 2017, Brendon revealed his beef with Boreanaz, saying that his co-star's refusal to perform the photoshoot with him resulted in Brendon having a much later start time.

David Boreanaz Constantly Revealed Himself On Set

It seems like every TV show has one-- that one jokester who's constantly trying to elicit a smile or laugh out of their castmates. They'll prank and shock their fellow actors just to see how they'll react. For the Buffy crew, that jokester was David Boreanaz.

According to Sarah Michelle Gellar and "Queen C" Cordelia Chase actress Charisma Carpenter, Boreanaz was constantly testing his co-stars' ability to stay in character. The ladies revealed that Boreanaz would frequently walk out on the set with no pants (or with a modesty sock) to see if his co-stars could keep a straight face while on camera.

Adding icing to the cake, Carpenter accused Boreanaz of being surprisingly "giggly." Boreanaz apologized (sort of) for his behavior at the 20th-anniversary reunion. The actor said he was sorry, shrugging and laughing all the while.

Sarah Michelle Gellar Is #TeamAngel All The Way

 Buffy and Angel dancing on Buffy The Vampire Slayer

The Buffyverse debate to end all debates: Spike or Angel? (Sorry, Riley.) Every Buffy fan has their preference and they'll fight tooth and nail to prove why their ensouled vampire belongs with the diminutive blonde slayer. However, Sarah Michelle Gellar has her preference, too, of course.

Obviously, Gellar has been asked which pointy-fanged boyfriend she prefers for Buffy many times over the years, and her answer has never changed.

From her Reddit AMA to the show's 20-year reunion, Gellar never fails to share her unending loyalty to her first love.

The actress even celebrated National Angel Food Cake Day (who knew that was a thing?) with a photo of a mock wedding cake featuring little Angel and Buffy toppers. So that pretty much settles that.

 He Is Not Spike's Sire

Spike and Angel Holding Hands

You could be forgiven for assuming that Angelus created Spike... they said as much in the show, after all. In season 2 episode 3 "School Hard", Spike comes across his old friend Angelus only to discover that the centuries-old vampire has lost his bite.

A disappointed Spike yells at Angel, "You were my Sire, man. You were my Yoda." However, this wasn't actually true.

Okay, so the Yoda thing is pretty accurate-- Angelus taught Spike how to be a vampire. They palled around through a series of historical eras, getting up to shenanigans and drinking blood to their hearts' content.

However, he did not create Spike, Drusilla did. Joss Whedon attempted to cover up the mistake, saying that the Angelus would actually be considered Spike's "grandsire" but this term does not exist in the vampire world.

David Boreanaz Says That Darla Is Angel's Soulmate

Darla (Julie Benz) and Angelus (David Boreanaz) in Buffy the Vampire Slayer

No matter how much you might wish that Buffy and Angel could find a way to make their epic love story work, David Boreanaz has other ideas. According to the Angelus actor, Angel's true soulmate is Darla, and he's not without his reasons.

Boreanaz pointed out the obvious: Darla created Angel, which holds a lot of sway in the vampire world.

No matter what happens in his life, he will always be drawn to his sire.

He also mentioned the 100 years they spent in a relationship (though he admitted that it wasn't exactly a healthy relationship), as well as the fact that they made a baby together.

In Boreanaz's opinion, Angel eventually grew to the point where he didn't even think about Buffy anymore. We hate to admit it, but Darla's got a pretty good case here.

 He Was Cast The Day Before His First Scene Was Filmed

A key role, an epic romance, two television series-- Angel's influence was an important one, so you might assume that his character was well-planned and thought out from the start. He wasn't, though. In fact, Angel was such a last-minute addition that he was only cast the day before his introduction to Buffy in the show was to be filmed.

In season 1's "Welcome to the Hellmouth", Angel was not meant to be an important figure. Throughout the first and second seasons, he was meant to be a love interest for Buffy and nothing more.

Pressed for time and desperately seeking an actor to inhabit Buffy's potential boyfriend, execs cast Boreanaz in his eventually iconic role at the very last minute. The next day, Boreanaz was on set getting thrown around by the Slayer herself.

David Boreanaz Was Discovered While Walking His Dog

In order for fans to get behind Buffy, the titular character of the series and savior of the world, falling in love with a vicious killer vampire, showrunners believed that whoever played Angel would have to be attractive-- really, really attractive.

Attractiveness was the main criteria when it came to auditions.

A friend of Buffy casting director Marcia Shulman saw Boreanaz walking his dog every day and knew instantly he was the person who Shulman was looking for.

Boreanaz was brought in to try out for the role and impressed the showrunners with his looks and acting talent, securing himself a spot in television history. Boreanaz has always remained thankful to his four-legged friend for aiding in his acting career. He owes it all to Bertha Blue and he knows it.

Nathan Fillion Auditioned For The Part

Nathan Fillion as Caleb - Buffy

It must hurt to know that you lost the role of the "Most Handsome Man Ever." Nathan Fillion auditioned for the part of Angel but didn't even make it past the first round. Of course, clearly, Fillion left a mark on Whedon and the other Buffy showrunners, and he was brought back as the evil Priest Caleb in season 7.

Fillion's Firefly auditions were just as troubled, though. He had to endure five rounds of try-outs before he landed the gig. Fillion admitted that he hadn't shown very much variety in his script-reading and the showrunners were worried that he was one-note and couldn't take direction.

In his fifth and final reading, he finally asked the execs what they wanted from him and was able to give an impressive performance at long-last.

A Quick Scene Convinced Joss Whedon David Boreanaz Was A Star

It's rumored that Angel was meant to stay dead after Buffy sacrificed him at the end of season 2. The legend states the character was so popular that The WB insisted on a spinoff, so Whedon decided to bring him back.

Over the next season, as Angel was being set up, Whedon would have a crisis of faith on multiple occasions, but Boreanaz always managed to pull through.

Both Whedon and writer/producer Marti Noxon have hailed season 2 episode 19 "I Only Have Eyes For You" as the moment when they knew that Boreanaz was an acting powerhouse.

While filming season 3's "Bad Girls", Whedon wondered whether he'd made a mistake creating an entire series based on the vampire.

In one scene, Balthazar screams at Giles and Wesley, wanting to know the name of the man who holds his stolen amulet. Boreanaz sweeps in and responds, "His name is Angel." Right then, any doubts Whedon had were put to rest.

The Love Scenes Were Massive Prank Wars

Angel and Buffy kissing in 'Revelations'

As Buffy's first true love, David Boreanaz had to kiss Sarah Michelle Gellar a lot. That's an intentional choice of words.-- he didn't get to, he had to-- it was his job. However, for Boreanaz and Gellar, romantic scenes were anything but. Though this was largely due to their own fault.

Gellar revealed that she holds no jealousy toward women who participate in love scenes with her husband, Freddie Prinze Jr. To her, love scenes are awkward and uncomfortable.

To combat this, she and Boreanaz would put each other at ease by pranking each other any time they had to get up close and personal. Gellar would sew her clothing shut to make it difficult to remove and the pair would eat foul-smelling foods like tuna and pickles before they got to smooching.

 He Was Still Closely Tied To His Irish Heritage Centuries Later

Angel spent centuries traveling the world. He took in Asian culture with Darla, he spent time in England and France, and of course, he ended up calling sunny California his home. However, throughout all of it, Angel clung tightly to his Irish heritage... even if he did end up losing his atrocious accent.

Angel shares his heritage with Buffy in season 2 episode 13 "Surprise" when he gifts her a Claddagh ring for her 17th birthday. He explains that the ring symbolizes love, loyalty, and friendship and shows her how to wear it to represent her relationship status.

Then there's Angel's mysterious tattoo.

The tattoo is an image of a griffin taken from the Irish book of gospels, The Book of Kells. 

Joss Whedon once joked that he didn't realize the tattoo had so much meaning-- he simply assumed it was a bird.

 He Appears In More Episodes Than Any Other Character

Not even the Slayer herself holds the record for the most Buffyverse appearances-- nor do Cordelia or Spike, despite them being staples of both series.

This distinction belongs to none other than the vampire with a soul: Angel. Angel was present in both Buffy the Vampire Slayer's series debut and finale episodes, as well as both the first and last episodes of his namesake spinoff Angel.

As the star of his own show and a super important presence on the original series, Angel was featured in more episodes than any other character in the Buffyverse. Angel appeared in 57 out of 144 Buffy episodes. He was featured in all 110 episodes of Angel. All told, the broody vamp turned up in 167 total Buffyverse episodes.

Joss Whedon Thought Angel Was The Most Difficult To Write

Joss Whedon has created many interesting and compelling characters over the years. We've watched them learn and grow, we've watched them struggle, and we've watched them succeed.

Xander grew from a dorky screw up to a hero in his own right. Willow overcame addiction, loss, and struggles with her orientation. Despite all of the controversial subjects broached in the Buffyverse, Whedon thought that Angel was the most difficult character to write.

During a Reddit AMA, Whedon admitted that he had a tough time turning the handsome hero with a decent of morals into a compelling character.

Obviously, Whedon got around this by inflicting the curse on Angel, making it possible for the stalwart hero to go rogue at a moment's notice. Angel's soulless evil personality Angelus, however, was a different story entirely. Whedon had a blast writing for the vicious vamp.

David Boreanaz Did A Majority Of His Own Stunts

David Boreanaz didn't just perform his own brooding when he took on the role of Angel, he also performed most of his own stunts. Throughout both Buffy the Vampire Slayer and Angel, Boreanaz was responsible for two-thirds of his character's stunts.

Running, jumping, and, of course, kung-fu fighting, Boreanaz did it all. The actor was thrust right into the thick of it during his very first Buffy shoot when he was kicked and battered around by the Slayer during their first meeting.

Though he was always grateful for having had the opportunity to perform the stunts himself, Boreanaz began to rely on stunt doubles more frequently as he got older. He said he had started to realize that the stunt doubles were there "for a reason" and stepped out of the way so that they could do their jobs.

David Boreanaz Does Not Want To Be In A Reboot

Lots of actors become excited at the thought of reviving their past roles, especially super iconic ones. For example, Jenna Fischer can't wait to get her hands on Pam Beasley again and Danielle Harris was sad that she wasn't invited back into the Halloween franchise.

David Boreanaz, on the other hand, could care less if a Buffy reboot ever happened.

In a 2017 interview with Parade magazine, Boreanaz stated that he refused to participate in a reboot or revival under any circumstances. When asked if he would consider such a project Boreanaz said, "No, never; that's done, see ya, next."

Harsh words, but according to Boreanaz, he simply doesn't like to dwell in the past. He loved his time on the show, but he would much rather keep looking and moving forward.

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Can you think of any other interesting facts about Buffy the Vampire Slayer's Angel? Sound off in the comment section!