In this fanfiction, perhaps Thor hits Loki with Mjolnir as a form of punishment for one of Loki's many tricks. Maybe Loki has double - crossed Thor in a plan to take over Asgard, and Thor's only option to stop him is to use his powerful hammer.
It could be argued that Loki is also a kind of protagonist in his own way. Even though he is on the receiving end of Thor's hammer, his actions leading up to that moment are likely what drive the story. His schemes and plots are what cause Thor to react, so in a sense, he is a central figure in the narrative as well.
There's 'Thor's Redemption in Loki's Arms'. In this story, Thor realizes his true feelings for Loki after a series of events that nearly tear Asgard apart. It's a tale full of emotion and character development.
I really like 'A Different Path for Loki'. In this fanfiction, Loki is given a chance to redeem himself in a unique way. It's full of interesting plot twists and great dialogue between Thor and Loki. The author does a wonderful job of exploring Loki's psyche and his relationship with Thor against the backdrop of the Asgardian world.
If Loki survived in Infinity War fanfiction, it could have led to a very different outcome. He might have used his trickery to deceive Thanos in some way. Maybe he could have pretended to be on Thanos' side while actually working against him. This would have added an extra layer of intrigue to the story as the other characters would have been unsure of his true motives.
When Thor is mean to Loki in fanfiction, it can lead to a downward spiral in their relationship. Loki, feeling constantly attacked, may lash out in more extreme ways. Thor, on the other hand, may double down on his meanness, believing it's the only way to deal with Loki. This can create a cycle of animosity where any love or brotherly bond they had is overshadowed by anger and distrust. For example, Loki could start to form alliances with Thor's enemies out of spite, and Thor would see this as confirmation of Loki's untrustworthiness, making the relationship even worse.
Thor might initially go into denial. He can't believe that Loki is truly gone. He may hold Loki's body for a long time, as if waiting for him to come back to life. Then, he could become angry. Angry at the situation, at whoever or whatever caused Loki's death. Eventually, he may find solace in the memories of Loki. Remembering the good times they had together and using those memories to move forward.
In many cases, Thor eventually regains Mjolnir. However, the circumstances and challenges he faces to do so vary greatly from one comic series to another.
Thor lost Mjolnir in the comics because of various reasons. It could be a powerful villain's curse, or a moment of doubt within Thor himself that broke the bond with the hammer. Sometimes, external circumstances beyond his control also played a role.
These fanfictions typically show their relationship as something that has to be hidden from the rest of Asgard. It adds an element of secrecy and danger. The relationship is also often portrayed as a way for both characters to find solace in a world that doesn't always understand them. Loki's cunning and Thor's power are intertwined in a way that makes their connection unique and captivating.