Writers going for Tomtord redemption arcs often have to walk a very fine line, don't they? You've got Tom, the brutal, power-hungry wizard, and Voldemort, who is basically the personification of evil in that universe. Having either of them come around feels like it requires bending canon so far it snaps. I've seen a few that make it work by leaning hard into the 'Tom before he became Voldemort' angle, framing it as a desperate, last-minute snatching of a soul from the brink. The 'Harry raised by Death' trope sometimes gets spliced in, where Death itself intervenes and forces a kind of penance. But honestly, most of the time it just ends up feeling like a massive character assassination—Tom Riddle losing his cunning or Voldemort developing a conscience always rings hollow to me, like the writer just really wanted a happy ending for their problematic fave.
That said, I did read one recently that stuck with me, a crossover with 'Good Omens' of all things. It was a crack premise taken seriously: Aziraphale and Crowley accidentally adopt a wraith-like Tom Riddle post-Battle of Hogwarts and spend centuries trying to teach him empathy through baked goods and vintage records. It was so absurd it looped back around to being kinda profound? The redemption came from sheer, stubborn exposure to mundane kindness over an immortal timeframe, not some magical fix. It felt earned because it took literal eons, not a few chapters. More fics should consider that scale, I think.