History Series / TheKingEternalMonarch

* PowerWalk: When Lee Gon, Jo Young and Kang Shin Jae [[spoiler:finally capture Lee Lim]].

* BigDamnHeroes: Lee Gon and the entire Royal Guard, horses and helicopters included, come to the rescue when Tae Eul thinks everything is lost.

* CynicIdealistDuo: Jo Young, for whom cynicism and expecting the worst of others is in the job description, and Lee Gon, who despite his position and troubled past is a mostly cheerful person.

** Lee Jong In/Prince Buoyong and Lee Lim/Prince Imperial Geum. They come from the same generation of the royal family and both have been kept from ascending to the throne due to Lee Gon's greater claim. But while Lee Lim is set on reaching his goals by any means necessary which most certainly include killing Lee Gon, Lee Jong In seems content with living a life as a doctor and professor of medicine, occasionally being attended to by his nephew.

* TookALevelInBadass: Jo Eun Sub starts the series as a wimpy police officer who runs away from fights ... and then [[TakingTheBullet takes a bullet for Lee Gon]]; he also discovers his hospital room has been bugged and sets a trap for the assassin sent to kill him. [[spoiler: In the new timeline created by Lee Gon, he's now an agent in the Republic of Korea's National Intelligence Service.]]

* TheGoodKing: Lee Gon's [[OneHundredPercentAdorationRating approval ratings are constantly monitored and are always very high.]]

* CatchPhrase: Lee Gon's "You'll be beheaded" [[spoiler: until he's serious]]

* CoolCar: Na-ri has several really cool cars that only sit two people, apparently.

* EiffelTowerEffect: The statue of General Yi Sun-Shin is showed in its place in Seoul to indicate the scene is happening in the Republic of Korea, or at sea when the scene is at the Kingdom of Corea.

* EstablishingCharacterMoment: We first meet Lee Gon as a child, having the presence of mind to strip his uncle of his Royal title and have the Royal Guard apprehend him despite the fact he's eight years old and has just seen his father dying in front of him. He goes as far as reaching for the Four Tiger Sword to do the job himself. We first meet Jung Tae Eul working a case, easily besting a group of mooks and holding her own using both her smarts and ActionGirl skills. And then, we meet Lee Gon as an adult riding Maximus and refusing to take the concerns of his court -- like the need to find him a wife -- seriously. He also easily dismisses the Prime Minister's faux-romantic advances.

* NotHisBlood: When Lee Gon arrives with an unconscious Tae Eul at his palace, Lady Noh asks him if he's hurt, since he has blood over his face and clothes. He says it isn't his. (In the Korean dialogue, though, he says "it's just a stain.")

* PostVictoryCollapse: Tae Eul is barely standing after running from the bad guys for hours and barely escaping a truck ramming against her. When Lee Gon appears with the cavalry and saves her, she barely has time to hug him and say she's missed him before collapsing of exhaustion.

** [[spoiler:Lady Noh met Future Lee Gon and knew all along he would travel in time to that night. Even Lee Gon is quite surprised about this one.]]
** [[spoiler:The Yoyo Kid or Flute Spirit has been several people moving the characters' actions all along.]]

* RoyalsWhoActuallyDoSomething: The title character Lee Gon does everything. He's a mathematician, attends scientific conferences, plays an active part in the government, and was a serving [[CommandingCoolness Lieutenant Commander in the Kingdom of Corea Navy]], separate from his role as Commander in Chief of the Kingdom of Corea's military forces. And this is all ''before'' the plot starts. Later, even with Tae Eul staying one day in the Kingdom, he spends most of it fulfilling his royal duties.

* SweetAndSourGrapes: [[spoiler:Shin Jae]]'s selfless decisions are doubly rewarded in the final episode: [[spoiler:in the revised timeline, he's partnered with Luna in the Kingdom of Corea's police force. Lee Gon also manages to prevent the accident that put the original Shin Jae into a coma as a child, with the result that he's healthy and successful (and apparently quite wealthy) in the present]].

* TookALevelInBadass: Jo Eun Sub starts the series as a wimpy police officer who runs away from fights ... and then [[TakingTheBullet takes a bullet for Lee Gon]], and discovers his hospital room has been bugged and sets a trap for the assassin sent to kill him. [[spoiler: In the new timeline created by Lee Gon, he's now an agent in the Republic of Korea's National Intelligence Service.]]

* YouMustBeCold: Tae Eul wonders why she believed Lee Gon to go to the bamboo forest when it's freezing. Despite how angry she is at being fooled, she suddenly nonchalantly receives Lee Gon's coat as he passes her by.

* HollywoodNerd: The title character, though it's somewhat downplayed. Lee Gon is a mathematician who sometimes gets lost in the world of numbers, not emerging from his study for days on end. Due to his [[ShelteredAristocrat sheltered upbringing]] he's had little experience with flirting. On the other hand, he's also very good-looking, very fit and athletic, a former Lieutenant Commander in the Corean Navy and, lest we forget, a reigning monarch. And played by one of Korea's biggest stars.

* SupremeChef: Surprisingly, Lee Gon. Since there's a real risk of being poisoned, the only food he can eat without someone tasting it first is the one he cooks for himself.

* FlashbackCut: widely used throughout the series, usually to backtrack parallel events, to show how an event actually ended, or to do callbacks to explain the current scene.
* FlashbackMontageRealization: [[spoiler: both Lee Gon and Lee Lim realized at the same time that it was Lee Gon who saved himself as a kid.]]

** [[spoiler:It was Lee Gon as an adult who goes back in time to save his younger self.]]
** [[spoiler:Lady Noh met Future Lee Gon and knew all along he would travel in time to that night. Even Lee Gon was quite surprised about this one.]]

* YouMustBeCold: Tae-eul wonders why she believed Lee Gon to go to the bamboo forest when it's freezing. Despite how angry she is at being fooled, she suddenly nonchalantly receives Lee Gon's coat as he passes her by.

* SugarWiki/MomentOfAwesome: Lee Gon coming to the rescue with the entire royal guard, riding a white horse, and shouting "Save her! She's the future Queen of Corea!"
** Also, Lee Gon and Jo Young walking to stop the coup in the past.

* MomentOfAwesome: Lee Gon coming to the rescue with the entire royal guard, riding a white horse, and shouting "Save her! She's the future Queen of Corea!"

** Every time Tae Eul encounters Lee Gon for the "first time" she assumes he's a criminal (2019), a nutjob (2016), or a kidnapper (1994), leading him to say to her five year old self, "Your personality hasn't changed in 30 years". She never assumes he's a decent guy.