His charm and trickery might be muted. Since he's being controlled, he can't fully utilize his wits in the way he usually does. He might seem more robotic in his actions as he follows Thanos' commands. For example, his banter and sly remarks would be less frequent and more focused on whatever task Thanos has set for him. Also, his relationships would be strained. His brother Thor, for instance, would be very confused by his sudden change in behavior and this could lead to a rift between them until Thor figures out what's really going on.
If Loki is controlled by Thanos, his moral compass, which is already a bit skewed, would be completely in Thanos' hands. He might be made to do things that are even more heinous than his usual mischief. His pride would also take a hit as he is no longer in control of his own actions. He would go from being a self - styled 'god of mischief' to a tool in Thanos' arsenal. However, deep down, his true nature might still be fighting against the control, and as the story progresses, we might see glimpses of his real self trying to break free.
Loki would likely lose his usual sense of self - determination. He's normally a character who has his own plans and motives, but under Thanos' control, he would be more like a puppet. His actions would be dictated by Thanos rather than his own desires.
If Harry was the son of Loki, his confidence would likely take a different turn. Instead of the somewhat hesitant confidence he has in the original series, he might have a more brash and calculated confidence. He would be more aware of his potential power and be more willing to take risks. His relationships with his friends would also change. Some might be drawn to his new, more exciting and dangerous side, while others might be put off by the Loki - like traits emerging in him. He would have to learn to manage these new aspects of his character while still maintaining his core identity as Harry Potter.
In this fanfic, Thanos could be using Loki as a pawn in a much larger scheme. Loki, who is now controlled, might be used to start a war between different realms. However, Loki's own cunning nature and his relationships, like his complex relationship with Thor, could come into play. Thor might notice that something is off with Loki and try to break Thanos' control over him. This could lead to a series of events where Loki slowly regains his free will and turns against Thanos in the end.
Naruto would likely be more conflicted. His usually bright and positive personality might be tempered by the knowledge of his dark heritage. He might become more cautious in using his power, knowing the destruction Thanos was capable of. He could also be more isolated as other characters might fear his potential for evil.
Well, one possible plot could be that Thanos uses his mind - controlling powers on Loki to make him steal powerful artifacts for his collection. Loki, being under Thanos' control, has to go against his own nature at times. For example, he might have to target Asgardian relics that he would otherwise protect.
Loki would probably be defiant at first. He has a strong sense of self - pride and would not easily submit to Thanos's abuse. He might hurl insults and threats at Thanos, even though he is in a vulnerable position.
If Loki becomes an Avenger in fanfiction, his character would undergo a significant transformation. He'd have to learn to work with others, which is not his strong suit. This would force him to be more patient and understanding. His view of power might also change. Instead of seeking power for his own gain, he could start to see power as a means to protect the weak. His relationship with the Avengers would gradually reshape his identity, making him more of a hero than a villain in the process.
Loki and Thanos are the central figures. However, characters from Loki's family such as Thor could also be significant. Thor might notice the changes in Loki and try to rescue him from Thanos' control. Additionally, characters like Heimdall, who has the ability to see across the realms, could be involved in detecting Loki's unusual behavior and Thanos' influence.
He would likely be more conflicted. Harry was always a morally upright character, but with Thanos as his father, he'd have to battle inner demons. He might be more powerful physically and have a darker side to his personality that he constantly has to keep in check.
Naruto might become more sly. Since Loki is a trickster, Naruto could pick up some of his devious ways. He may not be as straightforward as he used to be.
Another possibility is that Loki teams up with other characters. He could form an alliance with the Avengers or some other powerful beings in the universe. Together, they could come up with a plan to stop Thanos. Loki could contribute his unique skills, like his ability to shapeshift and infiltrate Thanos' ranks, and then they could launch a coordinated attack.