To save time, I've mostly only highlighted details concerning the vampires. Skip the summary to the bottom for my analysis if you want (or search for ' end of summary ' using ctrl+f). EDIT: There is no winning or losing in a discussion.
---------------------------------START OF SUMMARY----------------------------------EP1:
Near the end, Jing Tian and Xue Jian were attacked by the vampires (still think they're more zombie-like lol). Chang Qing swept in to save them with his spells.EP2:
Chang Qing captured the vampires, and gave Jing Tian and Xue Jian two pills as well as the communication thing (walkie talkie pendant?). He also warned them of other vampires in the region. Chang Qing brought the captured vampires back to Shu Shan.
Elder explained that the vampires were originally human. In the beginning, there was only one. The poison-user poured the poison into the human to make it lose its mind, and attack other people. It was through this method that the evil poison would spread.
Vampires started acting up at Shu Shan, and another elder discovered that jolting the memories of the vampires might help (based on a vampire named Wen Xuan). Yet another elder noted that Tang Men is a clan of poison-using experts; thus they were suspicious. Chang Qing's teacher asked Chang Qing to go investigate.
Chang Qing went to Tang Men. Old guy verified that the poison from the vampires' blood is the most potent and evil of Tang Men's poisons. Chang Qing questioned if anyone from Tang Men knew how to concoct the poison.
The following day, Chang Qing, Xue Jian and Jing Tian went to the village from which Wen Xuan came. Jing Tian recounted that one fine day, all the women were taken from the village. Chang Qing sensed what happened, and then followed his trigram's detection to Da San Yuan gambling den. In the gambling den, Chang Qing heard mysterious crying.
It is revealed that Pi Li Tang's leader Luo Ru Lie collaborated with Tang Yi to try to take Tang Men using vampires, and that there are 300 male vampires in Pi Li Tang. Tang Yi saw that there was one female vampire, and Luo Ru Lie told him that the female is the source (and incubator for the poison), and the most powerful vampire. The female bit the man feeding her, turning the number of male vampires to 301.
Xue Jian and Jing Tian bumped into each other while investigating the vampires. They were attacked by vampires. Chang Qing came and kept the vampires busy while Xue Jian and Jing Tian escaped.
At Shu Shan, Wen Xuan mumbled about not hurting people wearing red. Chang Qing's fellow disciple conveyed this message to Chang Qing, aiding him in delaying the vampires.
Xue Jian and Jing Tian were trapped. The vampires dared not touch Xue Jian as she was wearing red, and upon hearing the message from Chang Qing, Jing Tian stripped to his red underpants. Xue Jian and Jing Tian were able to fend off the vampires, and escape. Chang Qing kept the vampires in check, and after his fellow disciples arrived, they nabbed the vampires with a spiritual net.
At Pi Li Tang, Tang Yi questioned Luo Ru Lie why he let the vampires out, and was in turn questioned by the same person about his motives. Luo Ru Lie showed that he can control the vampires with his zither music. EP3:
Chang Qing, his fellow disicples and the members of Tang Men met at the main hall of Tang Men, guessing what the vampires' unwillingness to attack those wearing red meant. Tang Men concocted a cure for the vampires' poison.
Chang Qing cured the vampires at Shu Shan using the antidote from Tang Men. Wen Xuan wakes up, and reveals that Pi Li Tang kidnapped his mother, and begged the Shu Shan guys to save her.
Flashback of Pi Li Tang's mass kidnapping of women from the village, and forcing them to drink the poison. Wen Xuan's mother had the strongest will to survive for Wen Xuan, and so, was picked to be the source. Men who were kidnapped were bitten by Wen Xuan's mother, turning into vampires themselves. Wen Xuan was only scratched because his mother recognised him. Wen Xuan escaped, and infected others outside Pi Li Tang (which was unintended by anyone). His memory of his mother wearing red led to those attacked by him to avoid attacking those wearing red.
Wen Xuan also recalls that all the vampires infected by his mother had green eyes, except for him. Chang Qing's fellow disciples didn't remember encountering any female vampires, or any vampire with green eyes. Chang Qing deduced that there are stronger vampires in Yu Zhou City.
Luo Ru Lie released his army of vampires in Yu Zhou City after playing them a tune on his zither.
Jing Tian, Bi Ping and Mao Shan ran into green-eyed vampires at the city gates. Jing Tian attempted to use red cloth to stop them, but failed (because they didn't originate from Wen Xuan). Jing Tian found out that holding one's breath can also prevent detection by the vampires. Xue Jian bumped into vampires, but was saved by Jing Tian and Mao Shan (who were unaware it was her). Jing Tian and Xue Jian kissed to stop breathing (thus avoiding detection by the vampires) while Mao Shan held his breath (nobody wants to kiss the fatty
). Eventually, Mao Shan let out hsi breath through a bamboo pipe, luring the vampires away from Jing Tian and Xue Jian.
Jing Tian and Xue Jian contacted Chang Qing using the recovered walkie talkie, and he sent them the Huan Yin Di and a brush. Chang Qing also told Jing Tian and Xue Jian to use the Huan Yin Di to play the An Hun Zhou to control the vampires. However, there is a usage limit of 8 times, and the Huan Yin Di have to be used together with the pen in order to work. Chang Qing then sent them the score for the An Hun Zhou, and the drawing for the talismans. He was interrupted by an agitated Wen Xuan. Jing Tian discovered that the vampires were organised, and headed in the same direction.
Luo Ru Lie continued playing on his zither, thus remote-controlling the vampires. Xue Jian and Jing Tian saw the vampires headed for Tang Fortress, and went to warn her people. Tang Tai asked Xue Jian where the Wu Du Shou (holy beast handed down from generation to generation of leaders of Tang Men) was, but Xue Jian didn't know. She went to ask her grandfather, only to find him gone.
Luo Ru Lie held Xue Jian's grandfather at Pi Li Tang. He revealed himself and Tang Yi to the leader of Tang Men, but was astounded to find that the leader was not surprised. Tang Yi told the leader of Tang Men that everyone in his household wished he was dead. The leader replied that Xue Jian was true to him. Tang Yi expressed his frustration at not being important in anyone's eyes. Luo Ru Lie promised that no one would touch the leader of Tang Men without his permission. He also promised the leader that he would give him news of Tang Men the next day.
Tang Fortress was overrun by vampires, and everyone was abandoning it. Tang Tai pretended to be loyal at first, but soon showed his true colours. Xue Jian and Jing Tian had a narrow escape from the vampires, and went to Bai Du Lou, the place where Tang Men stores and concocts its poisons. Xue Jian reveals that Tang Men's skills in poisons are only passed to males, and not females. They were unable to enter through the front door, so they entered through the rigged back wall. Tang Tai came to Bai Du Lou, and was almost devoured by the vampires. However, he was saved by Xue Jian's An Hun Zhou and Jing Tian's talisman drawing.EP4:
Jing Tian accidentally released one of the vampires, and he and Xue Jian had to hide in Bai Du Lou again. They accidentally stumbled upon a secret passage in Bai Du Lou. They went in the tunnel, and became trapped. After passing through several obstacles, they reached a fountain, in which they found a potato that turned into a flying fairy thing. With the help of the flying potato, Xue Jian and Jing Tian managed to pass through the secret passage. Jing Tian was scratched by a vampire, and started his transformation while in a room with Xue Jian.
Bi Ping and Mao Shan went to look for Jing Tian, and was mobbed by vampires. They were saved by Chang Qing (who, by now, is probably a superhero in the hearts of some), and the whole crew went to look for Jing Tian.
Jing Tian was attacking Xue Jian while the latter tried to keep him under control with An Hun Zhou and the talisman. Chang Qing and company arrived. Chang Qing's fellow disicple wanted to 'take care' of Jing Tian, but was stopped by Mao Shan and Chang Qing. He then reluctantly agreed to wait for the next morning, but warned that if one more person was hurt, he'd have to take action. Chang Qing then lured and trapped the vampires in Tang Fortress' dungeon.
Chang Qing and his fellow disciples recounted the earlier encounter with a homicidal and suicidal Wen Xuan. Chang Qing told Xue Jian about Wu Du Shou, and its ability to fix the damage done by the poison. Xue Jian said she didn't know where it was, but wanted to look for it (not knowing that the potato was Wu Du shou).
Morning came, and Jing Tian woke up, transformed into a vampire. He was afraid of the sunlight, had black nails and sharp teeth. Mao Shan came with breakfast, but found Jing Tian gone, leaving behind only a funny note.
Chang Qing went to Yong An pawnshop, believing that was where he would find Jing Tian. And indeed he did. Jing Tian removed his own tooth for fear that he would bite someone, unable to hold back the urges. Xue Jian offered to be bitten. Everyone (well, Mao Shan and Xue Jian) cried, and Jing tian ran out of the room. He ran into the flying potato, who was introduced as Hua Ying the Wu Du Shou. Hua Ying cured Jing Tian of his poison.
Hua Ying cured Tang Tai, after which she cured the whole bunch of other vampires. Hua Ying told the company that the leader of Tang Men was at Pi Li Tang.
Luo Ru Lie absorbed the internal energy of the leader of Tang Men. Tang Yi found out he was double-crossed by Luo Ru Lie. Tang Yi got into a fight with Luo Ru Lie, and awakened Wen Xuan's mother (the source). Tang Yi then escaped with the leader of Tang Men.
Wen Xuan felt his mother's awakening, and went to look for her. Jing Tian and company followed.EP5:
Wen Xuan was crying on the streets when Chang Qing and company caught up to him. This is because he accidentally tore the shirt his mother wove for him. Chang Qing then got the inspiration to locate Wen Xuan's mother using a thread from said shirt.
Meanwhile, Luo Ru Lie was still engaged in battle with Wen Xuan's mother. Wen Xuan's mother was overpowered by Luo Ru Lie, who used zither strings. Chang Qing and company arrived at Da San Yuan. Xue Jian recalled that she heard crying before at that same place.
Inside Da San Yuan, Xue Jian and Jing Tian accidentally activated a trapdoor leading to Pi Li Tang (which was under Da San Yuan). The pair ran around, looking for Xue Jian's grandfather. They were attacked by Wen Xuan's mother, who was under the control of Luo Ru Lie's zither music. Chang Qing and his fellow disciple came in the nick of time, managing to suppress Wen Xuan's mother with An Hun Zhou and the talisman. Wen Xuan came as his mother fell powerlessly. Luo Ru Lie then fought with Chang Qing and his fellow disciple. He lost terribly, and was severely injured.
Hua Ying then cured Wen Xuan's mother (and it was implied she cured the rest of the vampires too).
----------------------------END OF SUMMARY-------------------------
tl;dr version (my thoughts in italics):Overall Plot
Tang Yi (son of Tang Kun (and his concubine), who is the grandfather of Xue Jian and the leader of Tang Men) gave the poison to Luo Ru Lie (leader of Pi Li Tang), hoping that Pi Li Tang would help him take over Tang Men.Origin, Description and Countermeasures
Luo Ru Lie captured all the women from a village, and forced them to drink the poison, turning them into vampires. Out of all the women vampires, Wen Xuan's mother appeared the strongest, and most suitable to be the source (from which to spread the poison).
Luo Ru Lie then captured all the men from the same village, and let them be bitten by Wen Xuan's mother. So, they are effectively second generation vampires (these had green eyes). (Why didn't Luo Ru Lie capture all the people at once? My guess is that there was no space, and Pi Li Tang didn't have enough manpower. Did you see their clan's population and 'office space'? Also, Tang Yi mentioned that Pi Li Tang is a third class clan, so it's understandable that they don't have the resources to do so
Among the second generation vampires, Wen Xuan (the source's son) got away with only a scratch (the rest were held in Pi Li Tang). Wen Xuan then degenerated into a vampire (but unlike the other second generation vampires, he had red eyes). In his memory, his mother was wearing red. He didn't want to hurt his mother, so he avoided the colour red. Wen Xuan then infected a whole bunch of people outside of Pi Li Tang, and those people infected other people, resulting in quite a hullabaloo. He passed his thought of avoiding the colour red to the third generation (and beyond) of vampires originating from him. They also got his red eyes.
It is proven that Wen Xuan, and the vampires branching from him, is weaker. This is because they can be cured with an antidote concocted by Tang Men, whereas the other second generation vampires could not (or at least it wasn't proven). (Why was Wen Xuan weaker, if he was also bitten by the source? This is probably because Wen Xuan's mother realised his identity, and left him only with a light scratch.
When the time came, Luo Ru Lie released the other second generation vampires from Pi Li Tang as an attempt to infect the whole town, and take over Tang Men as ruler. These second generation vampires didn't have the instinct to avoid red instilled into them. However, as Mao Shan, Xue Jian and Jing Tian proved, they cannot detect anyone holding their breath. (Can Wen Xuan and his branch of vampires detect people holding their breath? It is unproven.
Then there was the method of combining An Hun Zhou played using the Huan Yin Di, and the talisman that was drawn using the brush (although it is uncertain if the brush has any actual use, because there were a couple of times where people just did the drawing motion without the brush). This could freeze the second generation vampires for an hours. (Question: Could it stop Wen Xuan and the vampires originating from him? Answer: This is unproven.
The pills that Chang Qing gave Jing Tian and Xue Jian at the beginning of episode 2 did something to counter the vampires for one hour. (Was it a vaccine that lasted an hour? A repellant? It wasn't specified. Why didn't Chang Qing go back to Shu Shan to transport tons of pills to the town to keep everyone safe for some time? Time? But he could transport things through the walkie talkie, as proven in episode 3. Not enough pills? Not sure about that.