That ring that was gave to him wasn't completely new to him. He used to wear it also before but in the past he happened to loose it some times before meeting with WonPil. And other times.
The memory of the Middle Earth is a little blur on some points for that reason. Because in some moments he wasn't exactly himself.
The ring has power on his mind that makes him become a loyal soldier of Sauron, a general for his armies.
This time the situation is the same, he has to go to Erebor with an army and take command of the mountain. So sad that Smaug died and he wasn't there to protect one of his babies.
To be clear this time is not as the usual because the memory to he blur is the one from Nortrig, his family, Shiinden, is not clear. He is even a little confused but in some way he thinks that the way is following Sauron's orders.

He is preparing the troops at Mordor.

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On the other side Deidara is not completely sure of what is going on, he told SangPil to call him during that travel but it happens that he is not even answering at his calls.
He cannot say he is not worried about the matter but since Jiko used to go more often at Middle Earth than him. So Deidara decided to ask Jiko and decide who else to go to Middle Earth and see what happened. With Jiko went WonPil and Wuxin and they started to look for them.

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When the kids arrived at Mordor the place was full of orcs ready for the battle and SangPil was talking with Sauron, in a way they probably never heard him, there is no chance to think that he is in his right mind.
He proposed them to help him in that battle, his own sons should follow his ideals. But at the refuse he didn't show his better side to them and a battle started. The battle was quite harsh but noone ended up severely wounded, the end arrived when they finally took the ring out of SangPil's finger and just to be sure destroyed it.
Jiko when arrived helped them with the wounds.

Since the kids already know where Deidara comes from they should know also where he came from. See the Shire, Dol Gundur xD and all the things he likes of Arda.
He prepared a journey and invited the kids to bring all they thinks that can be necessary. Obviously they were free to invite who they wanted.

It is afternoon and SangPil is waiting for them to go.

If you could use a word to describe the party what would it be? Trash
To start with SangPil ordered 16 cakes for each twin, to celebrate in on all the parties they lost. Then he invited all the important people in Xhuanghen so there are people that not even SangPil and Deidara know.
The remains of food will be enough for the servants and them to eat for a couple of weeks.
Last but not less important, the music is SangPil's genre. Unfortunately for the guests Deidara was still too weak and let SangPil organize.

At the moment he feels quite useless, he knows where his brother is and who has him but he is not supposed to go or do something. They worry he could make the situation worse.
Not being able to do anything else he decided to go to see what Deidara does at Zhendong mansion. He keeps going there at night and that disturbs him a lot.

He is walking while thinking about what to do to discover the truth, he is not the smartest and also in this case doesn't want to cause a fuss.

Their fight finished as usual, they finished at bed, he finally revealed to Deidara the problem about Jiko. He suffered in Cloud Recesses because if the diet and at the beginning he really risked to bite Deidara, that is why SangPil preferred not to make them stay too near.
Jiko is a little better because Christoph helped him to overcome the problem of thirst.

Deidara still decided that he should know better the other Pils and Yung, so he invited that part of the family for a party. Yeah maybe he would need to talk with the orcs to know what SangPil was like and know him more but they are disgusting....

The party is in the house of Snake at 20.