Board Thread:Questions and Answers/@comment-176.203.39.110-20190719131421/@comment-110.54.177.247-20200720072107

I agree with most of the theory. I will be adding some of my ideas and mixing other theories as well. So, credit for them.

The story starts around four hundred years ago, stella together with the other witches accidentally summon flugel/subaru as they are practicing the extent of magic allowed by the od lagna. However, the summon was incomplete. They were only summon flugel/saburo's soul. Thus, echidna(or the rest of the witches) fashion a body for him (that's why his appearance is different also he was given an A.K.A to fool the od lagna because they think he will upset it because of his unatural existance).

Flugel/subaro develop friendship with the witches along the way specially with typhon, echidna and stella. Note: their are other witches and warlocks at the time but seven young witches bond together as friends and people started to call them the seven witches of sin because of their respective witch factor).

Flugel/saburo also develop intimate feelings towards satella and vice versa. By the way stella was the youngest one who became a witch because she just recently recieved her witch factor envy at the time.

Flugel/saburo became fond of the world of re zero specially the magic as he explore all knowledge about it together with echidna. Together they develop artificial spirits. They created A fox spirit with echidna's essence, a cat spirit(puck) with flugel/saburo's essence and a loli with mix essence (basically flugel/saburo is the father and echidna is the mother. They also build their own respective library of knowledge and book of wisdom. However, on flugal/saburo case his books(gospel) is inferior to echidna.

In addition, Typhon was so fond of flugel/saburo she turn him into her apostle/disciple whether he likes it or not.

Now, because of all of this interactions. Satella develop envy/jealosy towards the other witches but she keeps them hidden.

along the way, flugel/saburo had adventure on the world and meets different people and befriend them. He meets a merchant named hoshin( like otto on the current timeline) and gives him ideas from his world to form many merchandise. He meet shaula and turns her into his apprentice. He saved a pregnant woman on delivery, she was put on his library. However, after giving birth the woman died leaving a triplet but one of the triplet also died leaving only two boys. He also meet a princess of lagunica, a monk, a young boy, a divine dragon, a powerful swordman and the aunt of her beloved satella. He also planted a tree along the way.

Now, a war broke lost across the world. Witches and warlocks found out that when they collected seven witch factor it is enough to control the Od lagna(fate/stay at night references-moon cell) basically becoming a god. So they killed each other on pursuit of power.

Flugel/saburo wanted to protect each of his friends, the witches. thus, he created a group for them. Together with satella and his friends and group marched towards each of the witches. Unfortunately each one died(specifics of the death is found on the season 2 of the anime or arc 4 of the webnovel). However, before they died, they passed the witch factor to flugel/saburo(now you may wonder why flugel/saburo because his existence is not normal thus, he has more compatibility however you may choose stella for this, either way, it depends, let's see how the author writes this off).

Now satella was the only one left among the seven witch of sin. Flugel/saburo was worried thus, he created a santuary near a waterfall were the witch of sloth died. Because strategicly, his tower(library) could basicaly guard it and he put satella there. While on the library. He together with his friends develop trials(defenses) and explore the possibility of controling also the od lagna.

Remember, how satella keeps hidden her envy/jealosy. All of those feeling were stacked up together with her feeling of loneliness, and anger. Thus, it exploded inside her, giving birth to her shadow... The WITCH OF ENVY. This shadow upon emarging engulf half the world.

Now flugel/sabauro tried to rescue her but it was too late. She was consume by envy. Her rage pointed towards him (take note of the crime of passion thing) because she sees the witch factors inside him to be a by product/proof of loved by the other witches.

Now, his friends protected him and together they fight the WITCH OF ENVY. However, they could not defeat her. Now during the fight, they found out the properties of her authority of Envy and the only way to defeat her is to seal her.

Now, with all combine power(power of friendship) they were able to seal her. But, flugel/saburo loved satella so much that he wanted to save her from this predicament and wanted to stabilize the re zero world as it only has half of its entirety. He rush towards the tower and open THE DOOR that connects to the Od lagna. Being loyal to him some of his friend went with him this include a monk, a young man, a princess, two young boys, and an elf. Before leaving he instructed his apprentice to protect the tower and the witch santuary(where the WITCH OF ENVY is currently sealed) and lay down some rules of the tower, he also said to her that she could proxy/claim that she is one who sealed the witch as Flugel/saburo is so ashame to admit it.

As they enter THE DOOR. They were warped around. And instant, Now they are floating around the source of all... the Od lagna. Because flugel/saburo only has 6 witch factor he could not fully control it. However, by some miracle, he was granted some wish. One is to stabilize the re zero world and saving satella. But, the act of saving her will eventually undo her seal. However, Od lagna took her physical body and transform it into a baby girl (now incase your wondering, the seal was to prevent the WITCH OF ENVY going rampant. this seal is similar to sleeping beauty syndrome as it sealed away her soul).

Now, as he holds the baby girl, he thinks that satella will have a new life starting from zero. Thus, a new name is required. He named her EMILIA. He wanted/wished the best for her and he wanted her to be happy. This feelings even though inside the field of Od lagna sparked the cat spirit as he breaks his contract to echidna leaving puck to have problems in his memories while still having this feeling towards emilia he practically searched for her to fullfill this wish. (note: puck is also known as the beast of the end because of flugel/saburo essence as it is unatural existence on the re zero world).

Now, while holding the baby on his arms. They return to the tower. However, time inside the Od lagna flow differently from the re zero world. Almost 300 years had passed ( note: it can be 250 years or so or 293 years).

Because of trauma and burden of the witch factors, flugel/saburo is on death bed. He gave emilia to her aunt fortuna and asked to take care of her. He also instructed his friends to seal information regarding the Od lagna and to protect his remains as it contains the witch factors. And as he die he look at Emilia and smiled. Because of the incomplete summon his soul returns to earth and he wakes up feeling that he missed something as his eyes tears without warning.

Few days had passed, he walks to a convenient store to buy food. But later in a blink of an eye he was summon to another world... By stella. (now it is the start of the series).

Now, what happen to flugel/saburo's friends. Because of their absence the group that originally purpose is to protect the witches specially stella had been corrupted from the inside and thier views were twisted along the way thus creating two factions of the witch cult. The two young boys accidentally acquired the glutonny while carrying flugel/saburo body likewise the young man also acquired the witch factor of greed. But later passed it onto his son regulus. The princess also acquired lust factor and return to her castle but because of the witch factor she became mad and cruel(take note: because of the timeline she assumes a different name). Fortuna and geuse keep thier promised and take care of emilia. And also they carry the gospel given to them by saburo/flugel (now because of saburo's obsession to stars he gave them star nicknames based on their personality). - now this is the birth of the sin of archbishops.

Now, upon arrival to the rezero world saburo (now with complete summon). He has no power, he acquired it during his first loop when emilia named herself as satella prompting a shared experiences with satella. When emilia died and as subaro reached her hand. The witch factor of envy were transfered to him(take note:even though it can happen even if emilia never named herself satella but for the purpose of control over saburo it is required). The shared experiences also created a gap to form a contract with satella because technically emilia still is satella's body. Now saburo has the return by death ability.

I have an idea, saburo was not the first one called by satella while sealed. Al was the first one. Stella tried to summon saburo but failed the first time. This is also a plot for pride arc.