Well, Naruto's personality would likely undergo a significant shift. He would probably become more introverted as he tries to emulate Ulquiorra's detached nature. His usual boisterousness might be toned down. In his interactions with others, he could become more calculating, weighing the pros and cons more carefully. However, he would still retain some of his core values like loyalty and protecting his friends. So, while his outer personality may seem more like Ulquiorra's, deep down he'd still be the Naruto who cares deeply for those he loves. Also, his sense of humor might change from his goofy ninja jokes to a drier, more sarcastic kind of humor that Ulquiorra might have.
Naruto might become a bit more reserved. Since Ulquiorra is a rather cold and stoic character, Naruto could start to hold back his more exuberant emotions. He might also become more analytical, like Ulquiorra, when it comes to combat situations. Instead of charging in head - first all the time, he'd think more about the best approach.
If Naruto becomes a fan of Ulquiorra, his personality would change in multiple ways. Firstly, his confidence might take on a different form. Instead of being the loud and brash confident Naruto we know, it could become a more quiet, self - assured confidence like Ulquiorra's. He may also start to view life and death in a different light, similar to Ulquiorra's rather nihilistic view. This doesn't mean he'd lose his own positive outlook completely, but he'd have a more complex view. His relationships with his friends could also be affected. He might be a bit more distant at first, as he tries to figure out his new - found admiration for Ulquiorra. But over time, he'd find a balance between his old self and the influence of Ulquiorra, still being the hero we know but with a more nuanced personality.