Merlin

" I like the world of humans very much, but when it comes to each of them individually, I’m relatively, look, well, yeah! Very well, I suddenly feel that some things are better left unsaid! "

Just like this, it is not like he is an ally of humans.

A young man who is like a wind blowing on the grasslands. Before him, anyone would end up letting the tension out of their shoulders - a refreshingly righteous person. Still, due to seemingly being quite lacking in terms of seriousness and such together with a lack of the sense of responsibility, one can see that Merlin may also appear as a shady con man. A rhetorician who, even while perceiving things in an objective manner and accepting the cruelty of the world of humans, turns it into something bright by saying things like: “But, it wouldn’t be fun otherwise, right? "

Despite being a hybrid being, Merlin has never hated humans. Rather, he is fond of them to such a degree that it is beyond natural. He loves the world of humans, loves mischief, and loves girls. Generally, he is the Magus of Flowers who retorts at most things with a refreshing smile and a calm expression such as “now, now.”

As Merlin explains to Ana, incubi like himself do not have emotions of their own. They feed off of humans' dreams to harvest “subtleties of the heart” from them. They then expend those harvested emotions as fuel to feel emotions themselves.

Openly like this, he tends to appear as having a perfectly happy personality, a perfectly happy guy, without a single worry, but since Merlin himself is self-aware about the fact that he is a foreign body in regards to human society, he never crosses that last step... the wall called friendship. Ultimately, (just like a child who enjoys tasty food,) he is always watching over and protecting the world so that mankind can reach a happy outcome.

... So, if one is looking only at the end result, Merlin is a good man, and a wise one. But inside, he is an incubus, a being very far apart from humans. He, a being that consume dreams, can essentially understand human emotions, but cannot truly sympathize with it. He is an alien-like, inhuman being, who only rationally excuses himself inside a dream (dream = a human mind activity) and consumes it, and then leaves just like an insect. Due to this macroscopic evaluation criteria, perhaps he just cannot understand the human heart, unable to even know the actions of a person or to sympathize with it. Normally, he would be an identical being with the Beasts, an adolescent life form of a higher order that is certified as an enemy of humanity.

Merlin is very boastful about his abilities as a mage, claiming that he inflicts jealousy and envy on all other Servants, especially Casters, since they are second-rate to him.

It's a given that Merlin could see through the identity of the ringleader behind the Grand Orders incident. It's also a given that he stays silent about it. The human protagonist must struggle with his own power; it is only fate, for otherwise, they would only perceive their enemy as one they cannot defeat. Not even Merlin can surpass the last boss (the King of Magecraft) this time. Actually, on this basis, no Heroic Spirit can surpass him. The one who is destined to be able to surpass him is not a Heroic Spirit, but only a human who lives (now) in the present. Therefore, he shall watch over the Master, just as he had once watched over many kings in the past.

Merlin shall believe in the Master, the hope of human history; he shall lend his power to the utmost; and then he shall entertain himself relaxingly. Merlin's desire is to carve open a path for the protagonist's own destiny, to watch him off as he walks towards the future, to gaze at that kind of "beautiful view".

"After that, I'll just do as I always do; disappearing completely from everybody's memory. Most other things, I can do without much of a fuss. But this alone, I can never get used to."

Merlin is somewhat of an outcast, as his physical body has been imprisoned in Avalon, he lives a lonely life up in his tower. His eyes of clairvoyance provides an outlet for him to not be bored, to see the world at the present at anywhere he pleases. In this way, he is able to also use his magecraft to summon an illusion realistic enough to be its own person where he could essentially play out what he wishes to do in the real world, all while watching from his tower. His personality may make others believe that he is a shady con man, but he genuinely just wishes to help the Master as their story is beautiful. He loves stories with a beautiful ending and wishes to help guide the Master to finding their happy ending.

He does not believe in his right to feel emotions, due to his half incubus nature, he feels neither human or incubus, an outsider to both sides. In reality, he does feel emotions, yet his self confidence in his worth in having so is what causes him to simply put up a facade of laid back joyfulness as to simply be content. He deserves love and craves it, he is unfamiliar with emotions and love but he does want it. He simply needs someone there to show him how to handle and have his emotions, that he deserves to be loved and to love others.