Um he tried to believe in her right up until the very end so I think you're doing him a HUGE disservice. I mean we're really going to complain about actual flaws in a character (like lack of trust, even though you've seen that person, with your own eyes, become corrupted. Believing in Yulia to that extent would be exactly the same as giving jerk MLs a pass because the things they were going to do were prevented from ever happening) rather than fake flaws where treating an innocent person like sh!t is considered a mere mistake? I think it's more likely he did try to find out the reason for her behavior but was probably not only stymied in his efforts but also given false evidence that was impossible to refute, both because the villainess' father was involved and because the one who had the empress' ear at that time just had that much more power than he did (the fact is when he did finally break with her he STILL had his doubts, even struggling with that decision he had made before he ever had any clue she had changed). Also that most likely WASN'T Yulia at the time. Or did you guys not read the part where the father and daughter duo said 'Yulia is *back*'?
But he didn't even investigate. He didn't even try to figure out why she was acting so unusual after literally serving on the battlefield with her. He just sat there silently watching her fall into madness while playing the woe my love is suddenly a bad person. He apparently loved her and trusted her to the fullest extent but didn't notice she was being drugged? No matter how you spin it he was a bitch boy who allowed her to suffer and was going to kill her without much thought or care.
I think everything @rivers said encapsulates most of my temperament with Eusto
In close consideration of Eusto's character and the tampering of Yulia's character by the original villain father-daughter duo, Eusto was SERIOUSLY blind or lacking in motivation to see what was truly happening with Yulia. He didn't go past what what was beyond the exterior, instead stayed to where he could see her and made his conclusions.
Look at it like this... you stay with someone you look up to, for like 5-10 years. By then, you two have established each others' quirks, attitudes, heck maybe mind and muscle memory of each others temperaments, trust has been built, familiarity established. Suddenly, after all those years, they seemingly change. They become a violent hedonist who suddenly doesn't listen to you and what would you do?.. Sure, Eusto WAS innocent, but its innocent in naivete. If he loved her so much to a point of peity, he could've investigated thoroughly. He decided that the easier path (which, yes, was still hurtful and hard for him) was to execute her. There was no doubt to Yulia's actions, just him "Wow,,, she's changed. I cant seem to get to her, no choice but to kill her or were doomed." without asking why this is happening. Chapters 1-3/4 established it clearly that Eusto, who clearly could have easily identified Fez as the cause of this all HAD he investigated at all, instead, saw Yulia's behavior and fostered "seeds of rebellion". So, no, he didnt try to check things out, he was angry and wanted to clean the slate right away. I may sound too harsh on Eusto but Im not really THAT mad at him. I voiced out garbled thoughts for something I think was out of character for him and more than anything, I would go so far to say that I would pin this on the author more. I however did not clearly explain that. The flaw I dislike on Eusto is a reflection of the author's execution more than anything than it is an attack to him. He has his ups, especially being the only one to voice out displeasure for her tyranny in her face, but even then, that was the bare minimum. Again, author's execution. But separating them both, I just dislike Eusto for the lack of trust and probing because that is unlike how his character was introduced and I personally couldn't get over it. But more than that, I don't hate him.
Lastly, there is no way to equate Eusto = MLs who were ALREADY born jerks. Eusto is a chivalrous character, whereas there is no comparison to MLs who were grew to be jerks, cuz they're built on that premise. There's a difference to Eusto who was created in the concept of kindness and justice as his core hence he must embody that in chapters whereas you have an ML who has to unlearn the callous identity established on him by the author from an FL, thus, they're actions cannot be excused or prevented from happening because they were meant to have such a background to justify future scenarios. They are both two different characters embodying different characteristics and tropes.
So ye, while I wanna add more I think daz it since thisll be too long for anyone's comfort, really,.. orz this got long ╥﹏╥
last addition lmao: while i said all this, i AM in the process of forgiving Eusto. ive already given him enough flack for his incompetence and with the change in the results of the pre-determined story result, i would go so far to say that he does try his best for Yulia (he has the spirit) so ye, /shrugs
(hoping for the best)
Again, sorry tingz got long oomf ( ̄∇ ̄")
and i love Julia so much and if she's rly the empress, just with a reincarnation ala redemption arc as a korean woman, then Im all for it but what's not slipping is the fact that her supposed aide Eusto didnt even see the situation she was in being under the influence and manipulation of mf Fez like ???????????? make it make sense, you guys have history !! HISTORY !!!! YEARS TOGETHER !!! And you're not wondering why she went coo coo or curious enough to rly check???????????????????? fok dem constituents lol
i mean, kudos to obsessed orange-hair magician for the only one who had his doubts but im never getting past this info like wtf ???? i feel like, if i were Julia who was drowning and losing reason and the only ones i could depend on were the first ones to rebel on me with no clear investigation, id prolly cry LMAO ;-;