Merlin lacks a wish for the grail, as one could say she is “at peace,” with everything. Though she has her regrets, she is not arrogant enough to believe herself strong enough to be the one person to save Camelot  and right all the wrongs of her past - not a dig at Arturia there, because I honestly love her wish and adore her character, but it doesn’t fit Merlin. 

Not only that, but Merlin has come to terms with her past, and accepted her sins. Though they are a heavy cross to bear, she accepts the weight, and it’s a huge part of her development as both a person and a character for her to come to terms with how awful she at one point treated people and viewed humanity, while also treating both the knights and Arthur as tools to achieve the goal she desired. Thinking herself at one point to be on level with the gods, being imprisoned in that tower was probably the best thing to ever happen to her, as it gave her time to think back and realize “wow, I was a dick.” Sure, she got a bit suicidal and depressed along the way, but that was part of the process - for a being who had never felt human emotions and lacked morals prior, to look at Merlin as they are now, is proof that they have developed a ton. To her, going back and correcting the wrongs of the past is like kicking those who helped her change, and her time in her prison, in the face. 

To help understand it I guess, lets talk a bit about her history - Merlin’s imprisonment was for the crimes she had committed against humanity, ( though in the legends, this is often replaced with Viviane finding out Merlin was half demon/their origins, and she is disgusted, killing and or imprisoning them for it ) and in Viviane’s eyes, a just punishment they died for. Despite them both being otherworldly beings and having similar problems with understanding mortals, Viviane handled it a heckton better - being exposed to raising Lancelot, Bors, and Lyonell helped them develop and learn to accept humans as equals, whereas Merlin did not raise Arthur, but rather gave him away and then trained him when he was of age to begin fighting. There was no mother-son relationship there, where Viviane had it with their children. 

Her crimes were the blatant mistreatment of humans, and for her arrogance and pride. She viewed herself as god, and due to this, it led to the downfall of a kingdom, and many deaths. Yes, Camelot was a group effort, and yes, Merlin does sort of realize this - however, no one can deny she played a huge role, and Merlin’s big thing in the nasuverse is they are an inhuman immortal mage who struggled to view humans as individuals, rather than actual people. Like someone appreciating a painting, they cared more about the bigger picture then that of how the people were impacted. Death was never something they cared about, as sacrificing mortals here and there in order to save the world was worth it - however, no matter how “noble” one may think it is ( esp with that wording, Merlin was an asshole and flat out ignored people when they were dying and asking for their help ) it doesn’t change the fact that they did kill people, did cause suffering in a good amount of the population, and ruined lives. 

You can easily just say “Oh, it’s because of their origins!!” which, yes, did play a part in it: Merlin is the child of a mortal woman and a demon, and in some legends, the big S man himself, and this caused a lot of problems. After Blaise, her one parental figure was killed ( we don’t know why, they just disappeared from the myths, Blaise bb come back I miss you :’ ( ) Merlin was left an orphan, and raised themselves in the woods. With no one to teach them right from wrong, or really…anyone, in all honesty, around to even socialize with, this resulted in a lot of problems, becoming both emotionally stunted and unaware of what’s right and what’s wrong, so Merlin having issues with treating others as equals and seeing people as individuals vs toys she could move around the chess board to achieve her end game goal isn’t shocking, but rather disheartening :/ Expected, but still sad nonetheless. 

Her punishment was to be trapped in a tower in Avalon for eternity, being unable to leave and unable to die. She was already immortal, but being trapped in a utopia that literally no one could reach…yeah, she was doomed to be alive till the world itself ended. With no one else around and nothing to do, she basically sat and reflected on what happened for a thousand plus years, and came to terms with her history, and her treatment of everyone. She does have a big fear of people finding out and abandoning her - but I feel like that needs to happen to give her the final leap in her growth, you know? It’s the only thing she’s really running from now, being found out and losing someone because of it, or being judged. After going through that, I feel like her development arc will be complete, and she can finally start the healing process and become a new, healthier person.

It’s also important to keep in mind that Merlin isn’t a servant, as in the nasuverse, Merlin never died. Gilgamesh was able to summon them in Babylonia because it was a time before they were born, thus enabling them to treat Merlin as a heroic spirit, because they weren’t alive in that time period. As of Chaldea, Merlin isn’t a servant, but rather someone who is pretending to be, and is able to be there due to a Beast class skill they have ( which, I’m very eyeballs @, give me beast merlin pls ), independent manifestation. Due to the “world is ending pls help” situation in Chaldea, Merlin is able to bypass the laws of Avalon, as them leaving is for the sake of saving the world, and not just them skipping around in fields of flowers for the hell of it. 

So uh, yeah - TL;DR, Merlin has no wish, is at peace with everything, and even if she was to win the grail for her master, she isn’t a servant, and would give it to her master. 

Even if the sender had desired to remain unknown, their identity was obvious - for no other would seek her forgiveness, other than the being who had sought to punish the magician for their crimes. 

At one point, Merlin had been bitter - was a thousand nights spent repenting not enough to satisfy the ruler of the lake? Must she spend eternity watching the world grow old, to witness the downfall of the kingdom and king she had created over and over again? Perhaps, back then, she would never have forgiven them, despite having willingly walked into the spell. But now...

                             “ There is nothing left to forgive, Viviane. “ 

        “ Do not loathe yourself for the past. I do not regret the time we spent together, even if it ended in tragedy. As you once said... aimer ç'est ce qu'il y a d'plus beau. Thank you for the time we had, I shall always treasure it in my memories. “ 

Trees? That was certainly an interesting present to receive. Where the others charitable mood had sprung from she did not know, though she supposed it was better than nothing - and to turn down a gift, no matter how odd it may be, was never something she did. A present was a present after all, even if it was something like burnt potatoes from a certain knight, or pictures of trees from her fellow servant. 

          “ I see. I give you my thanks for these... exquisite gifts, dearest saber. If you would like, I could send you some flowers in return. An even trade, I think.  “ 

         “ Perhaps sometime I can also tell you of my time as a tree. While my beauty did not match any of these you have provided, I do believe you may enjoy the tale. “