For a Fairy Tail Mard Geer fanfiction, Mirajane could be an excellent character to pair with him. Mirajane has her own dark past and her demon powers which could relate to Mard Geer in some ways. Their interactions could be full of mystery and tension. Laxus is another one. Laxus' brash and powerful personality would clash with Mard Geer's, creating a story full of action and power struggles. Additionally, Cana could be paired with Mard Geer. Cana's laid - back but also cunning nature could play off well against Mard Geer's more serious and evil demeanor.
One interesting plot idea could be exploring Mard Geer's past before he became a major antagonist in Fairy Tail. Maybe he had a relationship that was torn apart by the dark forces he later embraced. Another could be a what - if scenario where Mard Geer is redeemed and has to face the consequences of his past actions among the Fairy Tail guild members. A third idea is a fanfiction set in an alternate universe where Mard Geer is a hero instead of a villain, fighting against an even greater evil that threatens the world of Fairy Tail.
The OC's character can develop through conflict with Mard Geer. For instance, if Mard Geer attacks the OC's hometown in the fanfiction, it could fuel the OC's determination to become stronger and seek revenge. This would shape the OC into a more resilient and vengeful character.
In fanfiction, the relationship between Mard Geer and an OC can be quite diverse. It could be a relationship of enmity, where the OC stands against Mard Geer's evil plans in the Fairy Tail universe. Maybe the OC is a mage with unique powers that directly oppose Mard Geer's dark magic.
In some fanfictions, Zeref is portrayed as a more sympathetic character. Instead of just being the big bad, he might be shown as a victim of his own power or circumstances. For example, he could be a character who was forced into doing evil things and actually has a good heart deep down.
One possibility is that Naruto, with his determination, could adapt Zeref's powers in a unique way. Maybe he'd use Zeref - like magic to enhance his ninjutsu. For example, he could infuse Zeref's death - based magic into his Rasengan, creating a more powerful and dangerous attack. Another aspect could be Naruto's personality change. If he becomes influenced by Zeref, he might become more brooding and less of the cheerful ninja we know. However, his core values of friendship and protecting the village would still likely be there, just warped a bit by Zeref's dark nature.
Yes, there are likely some fanfictions out there with this concept. You can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. Just type in 'Naruto Brother of Zeref' in their search bars and see what comes up.
I'm not sure specifically which 'mard ko dard nahi hota story' you are referring to. It could be a story with a male character who is portrayed as being impervious to pain, perhaps in a cultural or fictional context where male bravado or stoicism is being explored.