SPOILER!! I saw other comments already spoil this but Reed is I think the 100th regression Thesellid who became angry at the “god” of his church and the world because he keeps regressing over and over again and thought this was the best way to end the world(or something along those lines). Ailette believed she is the 17th regression(or around this number anyways) and that her current Thesellid is the 17th regression but he is actually the 117th regression Thesellid who she accidentally saved. My memory is a bit iffy having read all this in one 18 hr plane ride in 2022 but IIRC her tutorial round did start at the 17th regression but somewhere along the way she went into this dungeon(?) to grab this “save point”. This dungeon she went to was actually where post100th regression Thesellid was imprisoned in after Reed was defeated by I think OG FL(?) and him dying again and again in that dungeon was supposed to “erase” his existence eventually but Ailette taking the “save point” stopped his suffering and “saved” him. IIRC that’s why it told her “thank you” as she was leaving. Anyways that Thesellid ended up regressing again into 117th Thesellid and took over the Thesellid in Ailette’s current timeline. (Btw there’s only one instance in all his timelines that Ailette is present as a transmigrator kind of like the Kim Dokja paradox in ORV). Anyways back to the “god” of their world, Thesellid’s god aka the OG god abandoned that world and so a different head “god” and his subordinates kind of took over cuz the OG god was like a nepotism hire or something like that(imagine that the gods are like workers in a company and Ailette’s god is a new supervisor that is good and means well and Thesellid’s OG god is a nephew of the CEO). Anyways to save the world Ailette ended up leaving the current church and established the new church for her god to get enough followers and belief in him to power the world. This is all rough memory but let me know if you have any other questions.

When I read the novel, the plot twist behind Reed shook me so much and when I thought that was it another bombshell dropped