Love in Pavilion Background Information

I don't know where to start, but here's the important background information about Love in Pavilion that will help with a better understanding of Sword and Beloved! I'll try to be as accurate as possible, but all these are from my memory.

Important Characters
Wangquan Hongye (aka Wangquan Fugui's father) is from the prestigious and powerful Wangquan Clan. The Wangquan Clan is considered the most powerful among the noble clans and is the leader of the Yi Qi Alliance (an alliance consisting of noble clans against demons). To the outside world, the Wangquan Clan is definitely powerful, but internally, the people there are like vultures (e.g., some elders and relatives). Hongye lost his father (the Clan Head) when he was a teen and was left to fend for himself and his younger sister. After the disappearance of his father, Hongye was not acknowledged as the Clan Head, but only as the Young Master/ Young Clan Head. Some bad people in his clan tried destroying him and his younger sister. Hongye had to grow up strong and manipulative in order to stabilise his position in his clan and also to protect his younger sister.

Dongfang Huaizhu (aka Wangquan Fugui's mother) is from another prestigious family, the Dongfang Clan, who are known for their Pure Yang Flames. The Dongfang Clan left the Yi Qi Alliance a while back (due to wanting peace). Because the Dongfang clan stayed away from the conflicts and politics of the Yi Qi Alliance, Huaizhu grew up kind, righteous, and gentle.

Masked Group: A "vigilante" kind of group consisting of the talented sons and daughters of noble clans. Their main purpose is to find the truth of the world, that is, why they are not allowed to go out of the boundary that Third Master Aolai drew. The members did not want to be acknowledged only for their noble backgrounds, but by their abilities. This is why they wear masks to hide their identities. The members include Wangquan Hongye (the leader), Wangquan Zui (his sister), Yang Yitan (from the Divine Eye Yang Clan), Li Quzhuo and Li Zizai (brothers from the Li Family), Zhang Zheng (from the Black Sword Zhang Clan), and Qing Muyuan.

Important Plot Questions:
Question: What happened to Hongye and his friends (the Masked Group)?
Answer: Hongye and a few members of the masked clan accidentally saw the future (20 years from the LiP timeline), and that impending doom was coming. The Masked Group wanted to prevent the dark future as well as find out the truth about their world. They broke out of the boundary and met the Black Fox, a terribly powerful villain that could manipulate minds and create illusions. Almost everyone met their deaths outside of the boundary, but they did not just die, they died by killing each other. The Black Fox made use of Yang Yitan's divine eye abilities to see through the weaknesses of everyone in the group and also controlled them to kill each other. Some of the members were strong enough to resist the control, but they could not bear to attack their friends. It was a massive tragedy. Due to the sacrifices of some members, only Wangquan Hongye and Li Quzhuo made it out alive.

Question: What happened to Huaizhu and Dongfang Clan?
Answer: The Dongfang Clan were attacked internally by Jin Renfeng (Dongfang Clan's disciple) who coveted the Pure Yang Flames power. Huaizhu's father, the Dongfang Clan Head, was killed by his own scheming disciple, with his blood absorbed by him in order to be able to use the Pure Yang Flames. At that time Huaizhu was already weakened due to other plot events when she accidentally found out that Jin Renfeng killed her father and took control of the Dongfang Clan. Huaizhu could only forcibly send her sister away and faced Jin Renfeng alone. She would've been forced to marry Jin Renfeng if Hongye did not come.

Question: Why is Huaizhu referred to as "concubine"?
Answer: After losing his friends to that tragedy, Hongye was lifeless, depressed, and staying in bed all day. He lost his sword heart which also weakened him. Only when his butler informed him that Huaizhu was in danger that he got up as rushed to the Dongfang clan as fast as he could. The only way that he could save Huaizhu and get her away from Jin Renfeng as soon as possible is to marry her as a concubine. Back then, for prestigious families, a proposal to the wife needs to be very grand and required weeks/months of preparation. Hongye had no other solutions because (1) he was in a weakened state after losing his sword heart and (2) Jin Renfeng had gotten too powerful. Hongye could only make a deal with Jin Renfeng by using the reputation of the Wangquan family to pressure him. Jin Renfeng also did not want to let the outside world know that he killed his own Master so they made a deal. Hence, to the outside world (even to Fugui), Hongye and Huaizhu were not in love. People who knew Huaizhu thought that she loved the Masked Group leader but did not know that he is actually Hongye.

Question: How did Huaizhu die?
Answer: After marrying Hongye and before she was pregnant, she tried attacking Jin Renfeng again and almost died if Hongye did not save her. From that fight, she got weakened even more. Women in the Dongfang clan have the ability to pass on their spiritual power to their offspring. Huaizhu exhausted all her remaining spiritual power when giving birth to Fugui. She wanted him to be their hope to do what she and Hongye couldn't do. 

"Third Master Ao Lai" aka A Lai /Ao Lai San Shao is actually the SML/2nd CP in the first series Red Moon Pact.  He was a legend, known as the warrior who went the "outside/barrier" and marked the border in order to keep the main antagonist/Black Fox in the dark void.  

Ao Lai San Shao was from the Ao Lai Kingdom. He fought with the Black Fox at the void, and created a barrier to keep the Black Fox out of the human world/six realms.  For many years, The Black Fox couldn't enter to cause chaos until it slowly found a way.  Ao Lai sensed the barrier is weakened, so he traveled to Tushan to collaborate with the Tushan Hong Hong, the Chief of the Tushan Fox Clan.  While there, he hid his identity from everyone, except the Chief.  He met Tushan Ya Ya who was Hong Hong's younger sister.  They were the second couple in the series. Because she didn't know his real identity at first, she named him A Lai, but had always idolized Ao Lai the warrior. Together, Tushan Clan, DongDang YueChu (FuGui's maternal cousin), Ao Lai, and other friends battled with Black Fox.  After they managed to deal with the Black Fox and seal the barrier, Ao Lai returned to his Kingdom to keep a closer watch, and Ya Ya had to stay and rule Tushan while Hong Hong cultivated.  

As for the spirit stone, I don't remember much about it. Maybe someone else who watched the series can comment on that.

Tushan Rong Rong was the third and youngest sister of the Tushan Fox Clan, after Hong Hong and Ya Ya.  The three of them were very sisterly and close.  They all lived at the Tushan area and oversaw the clan.  She didn't have as much screentime as her sisters.  After Hong Hong fought with the Black Fox and injured her core, leading her having to cultivate for a long time, Ya Ya and Rong Rong together guided Hong Hong with her journey. Ya Ya became interim Chief of Tushan Fox Clan with Rong Rong's assistance.