Niamh

This is me trying to condense an extremely large quantity of information into a smaller form until I can find some way to document the absolute mountain of lore that goes along with this story.

PERSONALITY:

Niamh is calm and quiet. He carried the air of someone mature beyond his years, but there's an obvious sadness that makes him hard to get close to. He's soft spoken and helpful, making him fairly easy to get along with on a shallow level, but he keeps the world at arm's length.

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After the goddess of the afterlife, Cathe was slain, Niamh and his fellow Valkyrie were created to gather the souls of the fallen in battle to keep some semblance of balance.
Eventually they were replaced and left with no duties left to fill. 

Being soft hearted, Niamh was far from the ideal Valkyrie. He was far too soft hearted, and struggled to fit in with his peers. Unable to find time to deal with him, his own division handed him off to another group until he was ready. This is where he met Halia, who took him under her wing and helped him come to terms with his duties by framing it in a new light.
Though being from a different division, even once he returned to his own the two still maintained good standing.

After losing his purpose he becomes friends with an immortal named Yulia, who invites him to become an adventurer alongside her. The two became inseparable, up until the goddess who created him, Moira, informs him that she's decided to destroy the immortals. Having destroyed the source of their immortality they can now be killed, and he and the other Valkyrie have been tasked with hunting them down. Afraid of the consequences Niamh agrees to participate, but cannot bring himself to hurt Yulia. Heartbroken that he's turned against her friends, she runs away from him, leaving him to find out that she was hunted down by another valkyrie. He struggles to mentally grasp what he's done and what has happened, and becomes paralyzed grief and indecision.
He is then given the order to strike Halia down- their new opposition, and his older sister figure. He struggles to go through with it, being unable to put any obvious effort into their confrontation. Not only is Halia far more powerful than he ever could be, but he cannot bring himself to hurt anyone else. Halia spares him, but makes sure he's too injured to continue the fight or come after him again. This angers Moira, who believes he lacks a proper sense of loyalty. After hesitating to fulfil his orders twice, Moira puts him under an enchantment as a leash to keep him in line. He becomes unable to raise a hand against her and is unable to disobey any direct orders given by her. 

After the main conflict betweenHalia and Moira, he gets dragged along since he's magically linked to Moira. He spends much of this time with his memories intact, trying to find any way to bring Yulia back as a way to undo his wrongs. As soon as they return to their own world he is the first to regain his memories. Realizing the chance he has, he finds Halia's old god slaying sword and decides to bring it to her so they can destroy Moira before she regains her status as a god.
The problem is that the sword turns out to be alive, hosting the spirit of a woman calling herself Laoise. She agrees to help him find Halia and they begin their journey together, eventually becoming friends. The two find they relate to one another, andLaoise reveals her history as the slayer of Cathe and the life she lead before she became the spirit in the sword.

I'm skipping a shitload of info because oh my god there is too much?? So anyways here's the entire god damn ending for this dude and co. :

At the end of the story they're given the power of the gods but limited use. They choose to use it to give the fallen immortals one last revival under the condition that they will age and die like everyone else. Both Niamh and Laoise decide to be reborn as well, giving up their immortality as well to try and be happy. Yulia refuses to forgive Niamh for betraying her and her trust, but tells him he'll have his whole life to try and make it up to her. The three begin anew as adventurers, with Niamh and Laoise eventually getting married along the way.