His character would become more disciplined. The Marines' training would shape him further.
Harry Potter's character would grow in terms of leadership. In the Marines, he'd have to take charge in different situations. His experiences at Hogwarts would still influence him, but he'd also learn new strategies and ways of thinking from the military. He'd become more patient and understanding of different cultures and backgrounds within the Marines. His magical side might be suppressed a bit, but it could still surface in unexpected and useful ways, making him a unique and valuable member of the Marines.
His character might become more worldly. At Hogwarts, he was mainly dealing with the wizarding world's problems. But in Shield, he'd be exposed to a whole new set of challenges and cultures, which could make him more adaptable and open - minded.
Harry Potter would probably develop a stronger sense of justice in the context of the BAU. In the wizarding world, justice was often about good versus evil in a very clear - cut way. But in the BAU, the lines can be more blurred. He'd have to learn to understand the complex motives of criminals. His relationships with the BAU team members would also shape him. He'd learn from their different perspectives and become more empathetic towards Muggles and their problems.
His character could become more rebellious. He might start to question the rules of Hogwarts and the wizarding world in general. For instance, if the gang has a disdain for the Ministry of Magic's regulations, Harry could be influenced to think the same way. This would be a big change from his usually rule - following self, at least when it comes to the good rules.
Harry's character would develop in many ways if he joined the army in fanfiction. He'd have to learn to trust his new comrades as much as he trusted his Hogwarts friends. His sense of justice would be put to the test in different scenarios. For example, in the wizarding world, he was fighting against pure evil in the form of Voldemort. In the army, the lines between good and bad might be more blurred. This would force him to think more deeply about what he's fighting for and make him a more complex and mature character.
He would likely become more hardened. The Grey Wardens face constant danger and hardship, so Harry would have to toughen up. His view of the world would expand as he gets involved in a different kind of fight against evil.
Harry's character often becomes more shrewd and politically aware. In Slytherin, he has to be. He learns to use his wits in different ways than in Gryffindor. For instance, he might become better at reading people's motives and using that to his advantage.
His character could become more confident in his charm abilities. After all, the Veela are known for their allure.
If Harry joins the Varia in fanfiction, his character would undergo a substantial transformation. His moral compass might be adjusted as he is exposed to the Varia's different ethical code. He might become more ruthless in combat situations, as the Varia are not as restrained as the wizarding world in terms of using force. His relationships would also change. He would no longer be surrounded by his Hogwarts friends, but by a group of tough - minded individuals. This would force him to communicate and interact in new ways. His identity would shift from being mainly a wizard from Hogwarts to being a member of the Varia, which would influence his self - perception and how he presents himself to the world.
His character might become more adaptable. In Rias's peerage, he'd face different challenges and cultures compared to the wizarding world. So he'd have to learn new ways to interact and fight.
Harry's character would undergo a significant transformation. The Cullens' values of self - sacrifice and protecting the family would influence him. He'd likely become more empathetic towards non - human beings. His magic might be used in more creative ways to adapt to the Cullens' lifestyle. For instance, he could use magic to make their home more vampire - friendly. His confidence would grow as he learns from the Cullens' strong family bond.