I have just finish this and in my opinion,it's average. Not the "bad grammar,bad English,bad spacing and symbol" sh1t,but in "Author creative juice"...
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First,he is reincarnated by ROB who promised him a system and he turn out to be new Pennywise. A weak,1hp Penny-chan that just got it's buttock kicked by **** loser club. While he is good in planning at the start(He possess someone and then plant his mind seed inside every ***** in town,start a cult and plan to conquer the world through it even when he totally forgot about it and become what cliche petty villain is,aiming for the loser club only.)and also have minion which strangely he didn't ventured out even when system encourage him via fear and reputation point.
After he kill all the loser club member,he take his minion and spaceship(Outer space killer klown) and instantly isekai without caring for the world anymore. It's like "Ahh,I kill the poporing.I'm satisfied. Let's abandon all the cash item I bought in this character and go create another account and kill poporing again."
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Next world,he reborn as baby in Overlord anime world.A GENIUS BABY!!!!! While he live as normal genius baby and grow up skipping grades to college with lots of diploma,he didn't do anything about his pennywise persona. He just live as normal rich human(Plot armor let him be rich nigga.) With lots of time skip.
In the game,there's also lots of time skip with lots of filler which is truly nothing worthy to read. Like he become adventurer,kill his own minion to fabricate his own legend etc. And in the end of arc,he and Ainz fight in war against demon where he backstab and eat Ainz for his knowledge.
Now,can I ask why didn't he just eat him from the start? Or when they all still in human world,can't he eat the game character?And why in the world did he make such an elaborate plan to kill Ainz like "To tie a shoelace,first we must built a light saber." Instead of just kill him in private? And did I mention that he didn't touch or earn even one cent of fear point but still magically earn fear and reputation point because some plot armor makes the world turn tomb and use his in game character to start a cult? And at last,he lost his virginity here and also evolve to Old One which is still weak as fvck yet his true form have??? as his plot armor stat.
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Third,he goes to Potterverse in Tom meet Dumbledork era(While the old talking magic to the young,he literally knock the door,give Tom balloon,and close the door.). Then he stalk and scared Tom like some normal mobs while at least,he finally use his brain to buy mobs to kill, spread the cult and fear point farming.(Where is his killer klown and spaceship?Author forgot.Where is his overlord stuff?Author forgot.)
Then time skip to Snape era where he got a man cave of his own with his minion. Here,he throw a book on Snape head and do the 'Harry and the Chamber Of Secret' to him with instead of sapping his soul,he change Snape into flesh eating being(Maybe.Author is forgetful and not creative in his pennywise persona.). And the end.
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My personal judgement on this character is,he's weak. Like really weak. Author did give Pennywise all those eldritch lovecraftian power but he didn't know how to use it. From his dream controlling(Like,wtf?? Why would he make a **** girl dream of him in **** boy body and flirt in dream?? Are you a pervert??), his fear point grinding(He literally only haunt one small town that equal to smallvile where the only interesting thing is its sewer when he actually plan to spread tle fear through the world. And his excuse is 'I wouldnt spread too much fear so FBI,secret service,government wouldnt come ag do something to me.'. Can you believe that? Meanwhile,he ate children like snack.),his health point which strangely the regeneration cant heal,to his overall management(Author dream big,but he didnt know how to do it. Either he abandon it or he time skip.)
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I actually very excited when someone making a pennywise fan fiction because it's new to me. But then,author creativity juice is just plain water.
All in all,I'm happy to see someone who dare to publish his work. It's a very courageous step to me and I'm very much appreciated it. I hope you can keep writing and grind your creativity more.