After analyzing the creature with some penny-friends for a while (using information from the cinematic universe and the some ifo of the book), we've concluded the following about his nature and how to try to "understand" how works his nature, especially with regard to the emotional aspect:
His cognitive intelligence is equivalent —that is, his ability to learn and use what he has learned.— to that of an adult human, but his emotional capacity and ability to have feelings and emtions is equivalent to a 3-4 year old child (emotions are more universal and all living beings possess them, while feelings are more complex and constitute a personal decision of people, rather than an impulse like emotions, since they are part of morality and ethics). That's why, in all his canons, even though he has the power of a cosmic horror, he is also so pathetic and crybaby. Literally, when something doesn't please him or things don't go his way, he pouts, throws tantrums, and do huffs. Haha, I love him!!
And of course, his general behavior is very animalistic because he is a beast, not a person , one that tries to mimic humans even though he doesn't understand or comprehend them (and thats why he is very uncany valley). Furthermore, his emotions and mind is like that of a very young child, and toddlers are not very different from complex animals at those ages.(which is why in many cultures like mine, they are called "the creatures" instead of "children" or "the baby" lol).
And that's why he's not just another alien, and he's neither a hatchling nor an adult of "his species," he simply is like that and will be eternally because it's part of his nature due to his function being the counterpart of "the turtle" which is wise and "ancient".
These details of his nature within his lore help us understand why he isn't an immoral alien villain, but rather the amoral being he is. It's because of both his "animal" nature and his "little child" nature that he lacks the capacity to understand ethics and morality —morality begins to be understood very gradually around four and a half years old, and in a very basic and childish way and that childish understanding of morality is like, "If I do this, I will be punished or rewarded."— He knows he's causing harm and wants to do it because he feels euphoria, like a bloodhound feels euphoria when taken hunting (and wild animals also feel euphoria when hunting, especially if they can get many prey, like a "fox in a henhouse" And that euphoria is what makes the fox kill all the chickens even if it harms it in future, because the hens can't escape and that makes the fox euphoric.).
For example, while it may be difficult for some to understand and accept, a hunting or fighting dog wants to kill or attack and knows it will cause harm and pain, the animal knows that the cries of the other dog or animal are of pain, and wants to do it because it's in its very nature, in its genes through centuries of selective breeding, to want to do it, especially if it has experience, this can be observed in the fox domestication experiment, where tame foxes were crossed with other tame foxes and aggressive foxes with other aggressive foxes, and then the litters were switched and still resulted in aggressive foxes even though the mothers were tame.
But for a dog of these breeds, wanting to attack and Biting is no different than a Labrador wanting to jump into the water every time it sees the water even if it's its first time swimming, for the same reason (a very specific instinct). Similarly, a cat might want to play with its prey when there's no need to, a domestic cat with all its needs met doesn't need to "torture" a simple mouse so much (it would with larger prey like a rabbit because it would need to tire it out), but a feral cat doesn't play with mice because it needs to eat them as soon as possible since it has no humans to satisfy its needs
So his intelligence is similar to an adult human in some ways, but his emotional capacity, character, and attitudes are like those of a small child, and his "understanding" of things and the world, as well as his reactions and habits, are very animalistic, understood?
So, can he hate? Not exactly, he can "hate" in quotes in the sense that a small child "hates" something or someone, and that's more of a mixture of fear and anger with some resentment that he feels towards humans like the Losers' Club because he felt the pain and the threat of being able to die, and he also has a deep resentment towards Maturin because he can interfere with his plans in some aspects since they are counterparts of each other, just as he is very afraid of Gan (the "other"), but the way he demonstrates it always seems very equivalent to how a small child experiences it and that's why it always feels very animalistic, because also,the real hate is something rather irrational in general and that's why it's something you decide to have (with or without bad previous experiences with what or whom you hate) and resentment is more "rational" in the sense that there is a previous experience and a previous reason of the "why" (reason is not justification)
Of course, the word "hate" with Pennywise is used in the book because it's a word commonly used to describe negative emotions, just as "love" is used for positive things. But come on, do you really love ice cream the same way you love your mother? I don't think so. You like ice cream a lot, but you don't truly love it, whereas you do love your mother. It's the same with the word "hate." The words "love" and "hate" are simply used too randomly, without pausing to reflect on what it truly means to hate or love. But that's perfectly normal; I use those words that way too.
In Pennywise's case, his "hate" is because he felt physical pain and the fear of dying (and being humiliated or having his territory invaded, as in WTD, especially with Hallorann; because his routines were disrupted, and he really detests new things) I explain this because it's common to think that hate and resentment are the same, just as people often think that emotions and feelings are the same, when in fact they have their specific differences; that's why it's very common for all of us to have confused them as if they were exactly the same thing and without differences lol.
And well, if he can't hate in the strictest sense of the word, it's clear he can't love either, lol. Nobody and nothing can only have the capacity to love or only the capacity to hate (that's why animals don't love you, because they don't hate you either). So the closest thing to "love" that the creature could feel, as we've seen, is at most to have affectionate emotions, or rather, tolerance, like a kind of "imprinting" like that which wild animals that get used to humans and of course domestic animals, but in a stronger sense through artificial genetic selection which occurs in animals that evolved to be social, and well Pennywise isn't a beast that was created to be social; in that sense, Pennywise is more like a crocodile than a cat so to speak.
And he could perhaps even enjoy the touch by tolerating it, as we saw with Ingrid, since he never showed hostility towards her, nor did he seem to have true disgust towards her affection , when he makes that gesture of licking his mouth, some people thought he was disgust, but I've seen he react to disgust on other occasions and it's not like that; it seemed more like just licking the blood from his teeth like a lion, lol, but it doesn't matter endeed.
But of course, he's far from feeling love for Ingrid; she was simply his "Judas goat" and he let himself be "imprinted" on her and showed her some consideration, even being gentle in his touches, and he was also relatively kind to Bowers lol haha although of course so he could use him as his personal hitman, so he can undoubtedly have a favorite human whom he won't hesitate to eat if he's hungry and there's no other source of meat nearby, because it doesn't matter what's «special» about the human or what ability a human has like Dick Hallorann, there are millions and he is eternal and patient so he can wait to have another favorite human as long as he wants.
And even a human who was potentially useful to him in the near future, he didn't hesitate for a second to eat him. That human who could have been the most useful to him was General Shaw, which is why he had let him go at first until he recognized his smell and wanted to eat him immediately.
So no, he won't feel love any human. Love is an abstract, profound, and complex human concept, even more so than hate. Love is something that will make you die for someone else (and not out of instinct, like a dog might defend you, since the dog doesn't know it will die if it tries). Whether it's your mother, your child, your partner, your sibling, your friend, or even true love for animals and nature, it will make you willing to die for that cause (something many biologists and park rangers do literally every day because they face death threats daily).
So this cosmic clown is as intelligent as an adult human (or more), but his emotions and feelings, as well as his malice, are like those of a very young child or certain more complex animals (a frog is not the same as a chimpanzee, of course), and his capacity for morality is like that of a hurricane or a wolf so to speak . And honestly, it's terrifying that something so powerful and destructive as him has such a childish mind, a mischievous and evil child.
He is simply a cosmic force of nature, made to consume and be the metaphorical and literal representation of destruction, and we see destruction as "hate" and "evil". And that is why Pennywise is "hate and evil incarnate that destroys everything."
My beautiful creature as powerful and pathetic at the same time, like a huge cosmic baby.
