An 'abusive isshin fanfic' is likely a fan - created fictional work related to a character named Isshin that involves some form of abuse in the storyline. However, this can be a very disturbing and unethical concept if it involves real - world harmful types of abuse.
One common theme is the power of partnership. Since both Tarnished and Malenia are strong in their own ways, their coming together to achieve a common goal is often explored. For example, they might fight against a powerful enemy that neither could defeat alone.
One common theme is her battle prowess. Many fanfictions focus on her epic battles, either recreating them from different perspectives or imagining new ones. Another theme is her relationship with other characters in the Elden Ring universe, like her brother or other demigods.
I'm not very familiar with this specific 'isshin x karin lemon fanfiction'. However, generally in fanfiction, the 'x' usually indicates a romantic or pairing relationship. It might explore the relationship between Isshin and Karin in an interesting way. Maybe it has unique characterizations and plot developments centered around their relationship.
In lemon fanfiction, the relationship between Ichigo and Isshin can be quite complex. It often explores a more in - depth emotional bond that might not be fully explored in the original series. The fanfiction might show Isshin's paternal side in a different light, perhaps more protective or guiding towards Ichigo.
There is a fanfiction called 'Tarnished and Malenia: A Bond Forged'. In this story, the author beautifully describes the relationship between the two. It starts with their initial encounter and gradually builds up the connection between them through various events and interactions. The description of the characters' emotions and the world around them makes it a very engaging read.
Another theme could be power transfer. Given Isshin's own powers and Ichigo's growth, fanfics might play with the idea of how Isshin could further help Ichigo develop his abilities. This could involve training sessions or even some kind of power - sharing scenario that goes beyond what we saw in the original series.
The fanfic allows for exploring different scenarios that might not be possible in the original series. For example, their relationship could be developed in a whole new way, like in a AU (alternate universe) setting. This gives the writer and the reader a chance to imagine different storylines for them. Also, the way their individual backstories can be intertwined in the fanfic makes it even more interesting.
You can try looking on fanfiction websites like Archive of Our Own. There are often many well - written isshin x kisuke fanfics there. Just search for the pairing and browse through the results to find ones that suit your taste.