One possible scenario could be Anakin sacrificing himself to save someone he loves, like his children or his friends. In this case, he might face a powerful enemy alone and use his remaining strength to defeat the foe but at the cost of his own life.
One possible scenario is that Anakin might get inspired by the unique battles and combat strategies depicted in the fanfiction. He could start thinking about how he would handle those situations in his own way, given his skills as a Jedi and later as Darth Vader.
One possible scenario could be in the heat of a battle. Byakuya, facing an overwhelmingly powerful enemy, decides to sacrifice himself to protect his comrades. He uses his last ounce of strength to perform a powerful attack, but in the end, succumbs to his wounds and dies heroically.
In a 'ahsoka death fanfic', one possible scenario could be her sacrificing herself in a battle against a powerful enemy. Maybe she faces an overwhelming force that she decides to take on alone to protect others.
Perhaps Anakin would find the fanfiction to be an interesting diversion from his own experiences. He might see characters in the Death Battle fanfiction with powers similar to his own and compare their uses of power. For example, if there were a character with a lightsaber - like weapon, he'd analyze how they fought compared to his Jedi training. He could also be intrigued by new and strange powers that don't exist in his world.
In a fanfic, he could die from a poison or a slow - acting toxin. Maybe he was on a secret mission and got poisoned without realizing it at first. As the toxin spreads, he tries to fight it but eventually succumbs. This could add a lot of drama as his friends try to find a cure but are too late.
One possible scenario could be that she sacrifices herself to save Tony Stark. Maybe in a battle against a powerful enemy, she steps in front of a deadly attack meant for him.
Another scenario might be that Connor Kenway succumbs to an illness or injury that he has been secretly carrying. He tries to keep it hidden as he continues his duties as an assassin, but in the end, it becomes too much and he passes away, leaving a legacy behind in the Assassin's Creed Brotherhood.
One possible scenario could be that he is killed in a lightsaber duel by a powerful Sith opponent. Maybe this new Sith has some secret technique that Anakin couldn't counter.
In some fanfics, Eren's death could be a heroic sacrifice. For example, he might give his life to finally defeat all the Titans and save his friends and humanity. He could use his Titan powers in a last - ditch effort that consumes him completely.
Some fanfictions might explore a situation where Anakin is being manipulated by a powerful dark force or a Sith Lord. This dark influence makes him see Obi - Wan as a threat to a grander plan. So, he kills Obi - Wan as part of this dark scheme, not fully in control of his own actions. And this can lead to a lot of complex emotions and plot developments later in the story, like Anakin's further descent into darkness and how the other characters react to Obi - Wan's death.