As a nigh-immortal brawler who has lived for over a century, Wolverine is one of Marvel's older heroes. Over the many lives that Logan has lived, he's also fathered a number of children, including a few that are relatively hidden from the rest of the world. However, one of them was also secretly a magical fighter with the power to save the world on her own.
Now, we're taking a closer look at Reine du Rien, better known as simply Rien, the magically-empowered daughter of Wolverine who debuted in Charles Soule and Paolo Siqueira's Marvel Comics Presents before fading into the background of the Marvel Universe.
During an assignment in World War II, Logan and a group of soldiers found a demonic ritual being performed by a woman named Marie. In the chaos, Marie lost her focus and control over the gate she had created, The summoning of the demon killed everyone nearby except for Marie, her captured daughter and Wolverine. However, Logan was able to fight off the demon as it moved to kill Marie, and she was able to send it back to hell. Dying from the strain of the spell, Marie forced Logan to vow to fight the demon when it returned a decade later and to protect her daughter, Sylvie, who could do the spell in her place. Ten years later, Sylvie summoned Logan to help her combat the returning demon., and the pair agreed to do the same for as long as the world needed it.
The second time they met, a grown Sylvie seduced Logan after their battle with the Truth, and became pregnant. A decade later, Wolverine and Sylvie met for the last time, as she was killed by a sudden attack from the Truth. The next decade, Wolverine went looking for her family to complete his side of the battle but was tossed away by the family, who had taken up the challenge of protecting the world. The following decade, Wolverine led the X-Men into battle against the Truth, which led to the deaths of Cyclops and Storm. This was also when Wolverine learned that Sylvie had given birth to their daughter, who made it her mission to carry on in her parents stead.
Traveling the world looking for her, Wolverine was reduced to a shell of his former self by the time he found her. Revealing herself as Rien, the young woman revealed that she had been raised as a warrior only dedicated to combating the Truth whenever it appeared on the world. Blessed with her own claws and healing factor and taught in the ways of magic by her mother's family, she was the perfect nigh-immortal being to fight the creature. But she was also raised only to fight, a somber connection she had with her father, even her name is a reference to the fact that she is "noting" except her mission to protect the world at all costs. She's shown to be a fairly disciplined fighter, save for a quick temper that's reminiscent of her father.
Logan convinced her that they should venture into hell itself to kill the Truth once and for all. Finding the spirit of Sylvie, they're able to drag the demon to the night it first appeared during World War II. After seeing itself, the Truth lashed out at itself. Sensing an opening, Wolverine and Sylvie were turned into eternal protectors of their fight, with all four beings turned to stone. This left Rien in the past, alongside (a now very confused) Wolverine from this time period. The fact that Rien outright called him "father" before venturing off on her own only added to his considerable confusion.
Rien hasn't appeared since the defeat of the Truth, but her healing factor and magical experience means it's likely she's still alive somewhere in the world. Given the size of Wolverine's family now, it would be fitting for Rien to make an appearance on Krakoa at some point, even just as a secret weapon for the mutant race.