Demonic possession through Soul Fragments and Elemental Clones with the use of Shallot's Mirror served as Eren's saving grace.
He possessed distinct advantages in both these domains, and thus, he sought to find an effective way to utilize them and resolve the dilemma he faced.
This dilemma involved the conflicting goals of exposing himself to farm Origin Force Points and maintaining secrecy. It was akin to attempting to stay in a fed and fasted state at the same time, a notion often regarded as impossible.
Of course, this dilemma wasn't something he could solve with a snap of his fingers. He needed time and a safe place.
The butcher didn't want to do anything too eye-catching before making sure that his safety was assured.
This was why he disappeared from the Practitioners' society as a whole. His identity as the bonafide Demon Slayer created an ideal environment for him to do so.
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