Who : Hon Siu Lung
Who?! : Louis Koo
What's He Doing In Here? : A member of the elite task force, G7 in the 21st Century. He is smart, agile, some sort of a practical joker and is afraid of commitments, which is why after 7 years he still refuses to marry his girlfriend, Chung Qing. She is thus disappointed and chose to end their relationship and married another man. The end of this relationship is the biggest regret of his life, which is why he joined the secret experiment by Lei Siu Chiu with the promise that when he comes back, they will transport him back to before Chung Qing ended the relationship. Unfortunately, something goes awry and his life changes forever. He falls deeply for Kan Qing because of her looks, feels guilty over Tin Fong who is crazy about him and is grateful and willing to learn to love the gentle Jiu Sin, however his love life is as messy as his life as the teacher of Jiu Poon/Ying Zhing.
Reel Life Or Real Life? : No such person existed in historical records, so reel life.
Who : Lin Jun/Lou Oi
Who?! : Kong Wah
What's He Doing In Here? : A swordsman under Jiu Muk (an official of the country of Jiu), he was actually sent by Ngai state to assist Jiu Muk in his evil schemes. A highly-skilled martial arts expert who is both smart, brave and has little honour in him, a right-hand man to Jiu Muk. Lin Jun thinks highly of himself and is eager to claim credit. To make a name of himself, he resorts to unscrupulous means to achieve his ultimate goal of fame and wealth. And he is desperately in love with Wu Ting Fong though he could sacrifice him as well, when his right hand became paralysed and he was desperate to become a swordsman again when Ting Fong rejected his love. Became the student of the even more despicable Lou Oi , killed his sifu and became Lou Oi and later worked for Lui But Wai. He was the reason of Siu Sin's misery and became the lover of Chu Gei.
Reel Life Or Real Life? : As Lin Jun, nope. But it took me quite a while to realise as Lou Oi, he was the Lao Ai guy who was indeed the rumoured lover of the real Zhao Ji (Jiu Gei, in the series renamed Chu Gei), and was working with Lui But Wai to usurp power. He became a eunuch but was in fact a false eunuch, meant to cover for Lui But Wai and Jiu Gei's sordid love affair as well as being her lover himself. In later years he would unsuccessfully try to revolt against Ying Zhing but failed miserably. He was later executed.
Who : Wu Ting Fong
Who?! : Jessica Hester Hsuan
What's She Doing In Here? : An innocent, irritating, annoying and stubborn tomboy who fell deeply for Siu Lung. Thinking he loved Siu Sin, the Jiu princess who is also her best friend, she bravely gave up her love for him only to discover Siu Ling felt nothing for Siu Sin and yet she is rejected by Siu Lung and to protect her dignity, she gives up everything and leaves for motherland, the Chun state. On the way met, pitied, stayed and encouraged the wounded Lin Jun who betrayed her trust to gain favour with Lou Oi where she was raped. Suffered a fate worse than death but will survive since she is a strong woman. Rumoured that she will be the wife of Siu Lung.
Reel Life Or Real Life? : No such person existed in historical records, so reel life.
Who : Chung Qing (modern times)/Kam Qing(olden times)
Who?! : Sonija Kwok
What's She Doing In Here? : Chung Qing is the long time girlfriend of Siu Lung who left him and married another. She is the reason why Siu Lung went back in time. Kam Qing, a girl who looks like Chung Qing is famous for her beauty, grace and especially her talent, an outspoken and intelligent woman who is skilled in playing the Piano. Her husband died on their wedding day and she is said to be a virgin widow. She is in constant search of talented people to assist in her quest and admires the intelligence of Siu Lung. Later she will fall for him and in the book, she marries him.
Reel Life Or Real Life? : No such person existed in historical records, so reel life.
Who : Jiu Nga/Madam Nga
Who?! : Shuet Lei
What's She Doing In Here? : Both beautiful and glamorous as well as a lady with many charms, she was a fortunate and contented princess. Her husband died years before and without much protection for herself and her son, Jiu Poon, she became Jiu Muk's mistress who is forced to "entertain" many of Jiu Muk's guests and enemies, so that he could achieve his ambition. She felt an instant liking to the honourable Siu Lung and asked Siu Lung to be her son's teacher. She is one woman that nobody respects, not even her own son and yet she found the respect she craved in Siu Lung. In the end, she faced a fate far worse than death, but she died an honourable woman with integrity that none can match.
Reel Life Or Real Life? : No such person.
Who : Jiu Poon/Ying Ching (the future Shih Huang Ti)
Who?! : Raymond Lam Fung
What's He Doing In Here? : The son of Jiu Nga, and nephew to the Jiu emperor. Seen as the son of the sinner, Jiu Pun grows up having to endure the cold shoulder and bully of others. Jiu Pun became rebellious and leads the life of a hooligan who gets himself in all sorts of trouble, until he met Hon Siu Lung who tried to lead him towards the right path with the most unorthodox way. However, later into the series,we will discover that the real Ying Zhing died in state of Jiu and because Siu Lung desperately wants to go home, he orchestrated the switch of identity and Jiu Poon became Ying Zhing and later probably assisted by Siu Lung, he will become Shih Huang Ti.
Reel Life Or Real Life? : Check out HISTORY.
Who : Jiu Sin/Siu Sin
Who?! : Michelle Saram
What's She Doing In Here? : A gentle and kind Princess of the Jiu state, she fell for Hon Siu Lung who thought she was a palace maid. When she was forced to marry a ruthless Ngai Prince, she ran away only to go back after being found by Lin Jun. She was often the political pawn and though she realised that as a princess that is her fate and she envies the freedom that Ting Fong has, she nevertheless does not give up hope of finding a happier life. Later she was killed by Lin Jun/Lou Oi when she found out his secrets, before she had the chance to become Mrs Hon Siu Lung.
Reel Life Or Real Life? : No such person.
Who : Sin Yau
Who?! : Joyce Tang
What's She Doing In Here? : A ruthless and uncompassionate assassin for hire, dressed as a man who actually has a heart of gold, however cold she may have been towards the tragedies that surrounds her. She caused the death of Siu Lung's teacher for money, but he couldn't kill her when she helped him and guided him in his journey into Jiu state without hoping for any reward whatsoever. She later became a confidante of Ting Fong who teaches Ting Fong the way os the Assassin's life though she discourages Ting Fong from joining the dishonourable profession. She secretly works for an even more sinister character though in  away she still retains her integrity as she became an assassin since she was a little child to support the orphans, who just like her had no parents to care for them when she was little.
Reel Life Or Real Life? : No such person. Reel life.
Who : Chu Gei
Who?! : Yew Ying Ying
What's She Doing In Here? : A famed beauty, mother of Ying Ching (the future Shih Huang Ti) and mistress of the Prime Minister of the Chun state, believed to be the father of Ying Ching, she was held hostage for many years in the state of Chiu and inadvertently became the reluctant mistress of Jiu Muk. In this series, she is not as weak as one would think of her, she is ruthless and cunning as well.
Reel Life Or Real Life? :Her name in mandarin is Zhao Ji, which should be Jiu Gei and yet the author of the book which this series is based on renamed her Chu Gei, which is Zhu Ji. Anyway, she was indeed the favourite concubine of Lu Buwei (Lui But Wai) but he had no choice but to give her as a present to Yingzhing's father. She subsequently bore him a son, but rumours had it that she was still the mistress of Lu Buwei and that Yingzhing was indeed the Premier's son. Later, she, Lu Buwei and a eunuch rumoured to be her lover (a disguise to hide the fact that she was seeing Lu Buwei, and so Lao Ai was not a real eunuch) controlled Yingzhing's empire but Yingzhing quckly regained control. She was then moved far away, but not executed since she was his mother.
  Who : Wu Ying Yuen
Who?! : Wong Wai
What's He Doing In Here? : Father of Wu Ting Fung, caretaker of the Chiu's Emperor's elite horses and a thorn in Jiu Muk's eye, he is actually a spy sent by Chun state and is working secretly for the PM of Chung state to rescue Chu Gei and Ying Ching who have been held hostage in Chiu state for years. He trusts Siu Lung and is ably assisted by his assistant, Tou Fung. His children does not know they're Chun people. 
Reel Life Or Real Life? :Reel life. No such person.
Who : Tou Fong
Who?! : Jimmy Au Sui Wai
What's He Doing In Here? : Trusted and loyal assistant of Wu Ying Yuen and best friend of Hon Siu Lung, he assists them in the plot to rescue the Chun hostages. He is also the comic relief in here, as he spends a lot of screen time with Siu Lung who speaks in the modern lingo. 
Reel Life Or Real Life? :Reel life. No such person.
Who?! : Unknown
What's He Doing In Here? : Could be said to be the father of the Legalist school of thought (though officially there wasn't one who could claim that credit), he was an unappreciated genius from the state of Hon until he was recruited by Ying Zhing to be his advisor, whereby his theory was the basis of the Qin government. In this series , he is a stuttering, soft spoken man and a fellow friend of Lei Si advised by Siu Lung to serve Chun state. 
Reel Life Or Real Life? :Real life. His name is Han Fei Tzu. He was a stuttering genius who was not appreciated by the the state of Hon and so her served Shih Huang Ti and gave birth to the harsh school of thought where essentially, men are born innately evil and so all laws, more punishment based are enacted to curb such potential of evil. In history, I was told by a reliable source that he was later ordered to die by Shih Huang Ti because Lei Si who was jealous of the fact that Shih Huang Ti was about to honour him with a high position because of his famous writings had him thrown into jail and I guess he died there as well. Refer to HISTORY.
Who?! : Chan Kwok Bong
What's He Doing In Here? : The less smarter of the two between him and Hon Fei, in this series ghe is a close friend of Hon Fei and was advised by Siu Lung to serve Chun when he was not appreciated by the the state of Hon. 
Reel Life Or Real Life? :Real life. He later caused the death of Hon Fei who was the more capable man between the two of then, gained favour with Shih Huang Ti and rose to power as the premier (aka Prime Minister) and advisor of Shih Huang Ti, who took most of his advise. He was the reason why there was the in famous burning of the books, burying of scholars and etc. He helped Shih Huang Ti in forming Qin and advised him in governing issues. He outlived Shih Huang Ti and this man even falsified decrees to kill off his enemies, Meng Tian and Prince Fu Su. Despicable.  Refer to HISTORY
Who?! : Tsang Wai Kuen
What's He Doing In Here? : Scheming premier of the state of Ngai, the state where Jiu Sin was married of to, he also had an affair with Madam Nga and is scheming to take over the Ngai throne. 
Reel Life Or Real Life? :Real life. I was told he was indeed the premier of the Ngai state who tried to prevent the Ngai state from being usurped by Qin ( I am quite confused as to the name Chun and will check on that). I am not aware whether he intended to usurp the Ngai throne though.
Who?! : Kok Ming Fai
What's She Doing In Here? : We know the actress is a she but apparently she is playing a he in here and as suspected by Siu Lung who knew him from the historical records, that he was gay. In here he is the honourable high ranking official, trusted, respected by the Ngai emperor but hated by Sung Ling Gwan, also a "brother" of Kam Qing, close friend of Siu Lung and student of Chow Hin. 
Reel Life Or Real Life? :Checking.
Who?! : Yu Tzi Ming
What's He Doing In Here? : Teacher of Lung Yeung Gwan, god father of Kam Qing, he is also the astrologer cum fortune teller in this series. A good man. 
Reel Life Or Real Life? :Checking.
Who?! : Lei Chi Hung
What's He Doing In Here? : A high ranking and scheming official in the state of Jiu, he was the one who forced Madam Nga to do all that she did with her son as his hostage, hid and had affair with Chu Gei and is eager to recruit Siu Lung as his right hand man. He abandoned Lin Jun after Lin Jun's right hand was paralysed from the fight with Siu Lung. In actual fact, Jiu Muk is the illegitimate son of a powerful  person of the state of Cho and was in fact working undercover for the Cho state. In the end he was killed by Ying Ching/Jiu Poon for revenge. 
Reel Life Or Real Life? : No such person.
Who?! : John Tang Yat Gwan
What's He Doing In Here? : Rich young kid who built the time machine and asked Siu Lung to go back in time to take some photos but well, everything went wrong. 
Reel Life Or Real Life? : No such person but his name, and the fact that he is so rich and is the foremost in the business of technology, I believe he is probably a version of Li Ka Shing or his sons. Even his name is similar to the nickname given to Li Ka Shing, Lei Chiu Yan or Mr Superman Li.
Who?! : Kwok Fung
What's He Doing In Here? : The Premier/PM of the Chun state, in this series he is the long time lover of Chu Gei and the real father of the dead Ying Zhing. He wants power and rejects Chu Gei's advances when she came back after years as hostage in Jiu State so that his son could be the Chun King. Alas he would be engaged in fierce battle of wits with Lou Oi (formerly Lin Jun) and Chu Gei to win power and trust of the Chun King. A smart and shrewd man, he would of course have his wish realised when Ying Zhing indeed became the new Chun King.
Reel Life Or Real Life? : You'll see his name spelt as Lu Bu Wei but Lui But Wai and Lu Bu Wei are one of the same man. A very important historical figure in Chun Dynasty who later committed suicide. To read more on this guy's history, biography and many exploits and his influence on the future Shih Huang Ti and why he wasn't executed but in later years he committed suicide, check out HISTORY and look for his name.