Well, it might enhance his abilities in some ways. Since a Horcrux contains a part of a powerful dark wizard's soul, absorbing it could potentially give Harry access to some dark magic knowledge or powers, though it would also likely be a dangerous and unstable influence on his magic.
In this fanfiction scenario, when Harry absorbs the Horcrux as a child, his magical abilities could be greatly affected. His connection to magic could become deeper and more complex. He might find himself able to perform spells that are more difficult or even forbidden, because of the influence of the Horcrux's dark magic. However, this new power would come at a cost. The Horcrux's dark nature could corrupt his magic over time. He would need to constantly fight against the urge to use the dark magic within him, and it could also make him a target for other dark wizards who sense the dark power within him. It could also change the way he interacts with his friends and teachers at Hogwarts. Some might be afraid of his newfound power, while others might try to help him control it.
It can completely change the direction of the plot. For instance, if Harry absorbs the Horcrux early on, he may have to face different challenges than in the original story. He might become a target for both sides, as the good side could be wary of his new, Horcrux - influenced state, and the bad side might see him as a threat to Voldemort's power.
His personality could change quite a bit. The Horcrux's dark energy could make him more aggressive at times. He may also develop a sense of superiority due to the extra power, but also have moments of self - loathing when he realizes the source of that power is dark.
In some fanfictions, Harry Potter might absorb abilities through magical artifacts. For example, he could find a special amulet that transfers the powers of the previous owners to him when he touches it.
One consequence could be that his connection to Voldemort becomes even stronger. This might lead to him being able to sense Voldemort's actions and thoughts more clearly, but also make him more vulnerable to Voldemort's attacks on his mind. Since the Horcrux is a part of Voldemort's soul, it could also start to influence Harry's personality, making him more aggressive or moody at times.
His custom wand might enhance his magical abilities. For example, if it has a more powerful core, it could make his spells stronger.
Well, in many fanfictions, the bond with a phoenix can enhance Harry's magical abilities. The phoenix is a very powerful magical creature. Its magic might seep into Harry, making his spells stronger. For example, his Patronus could become more powerful as the phoenix represents hope and renewal, which are strong elements in Patronus magic.
When Harry stumbles without his glasses, it could initially disrupt his magical abilities. He may fumble with his wand or mispronounce spells because he's distracted by his lack of clear vision. However, over time, this could force him to become more adaptable. He might learn to use magic in new ways, like using magic to enhance his vision temporarily or using spells that don't require precise aiming. This would make him a more versatile wizard in the long run.
It could make him more cautious. After talking to the Horcrux, he realizes how devious Voldemort's magic can be and becomes more careful in his future encounters with dark magic.
They're interesting because it's a unique twist on the original Harry Potter story. It adds a whole new layer of complexity to Harry's character. Instead of just fighting against Horcruxes, he has to deal with being a part of that dark magic in a way.
One popular 'Harry absorbs Horcrux' fanfiction might be 'The Horcrux Within'. It delves into how Harry's character changes as he absorbs the Horcrux. The story explores his internal struggles and how it affects his relationships with his friends at Hogwarts. Another could be 'Absorbing the Darkness' which focuses on the magical implications of such an event. It shows how Harry has to learn to control the new power within him that comes with the absorbed Horcrux.