Harry is not the "good" one
By which I mean, Harry is not inherently a good person.
If you think Harry could never be as bad as Tom, never kill, never be cruel or evil then you fundamentally misunderstand his character and the story. The whole point of Harry is not that he is naturally or easily good, the point of him is that he chooses to be good. For that choice to be meaningful, it actually has to be a choice, meaning that he must then have the capacity and ability for evil as much as Tom does.
If Harry is naturally more "good" than Tom no matter what awful things Tom inflicts on him, if he is just too pure and incorruptible, then he is not really Harry. Harry is corruptible, Harry could've turned out like Tom. That's why they're so similar, that's why Harry relates to Tom. That's why he worries about turning out like him. Not because he finds Tom's choices unfathomably evil, but because he understands them.
If Harry was raised the way Tom was, he wouldn't necessarily turn out much different. If he was isolated and neglected and terrified in the same away, with no friends, no loving parents, no adults to support him, then their similarities would be impossible to ignore.
And if you want to show that Harry is choosing to be good and not just a natural born bleeding heart saint you need to make that clear, you need let him be cruel and selfish and violent sometimes, you need to show him falling before he chooses to stand up.
So much of this fandom feels the need to make Harry completely unlike himself. Going to immense lengths to make him nicer, kinder, more forgiving, more emotional, more stupid, more naive, more trusting, more and more of what he isn't in order to show that he is different from Tom. When the whole point of their connection, and Harry's eventual understanding of Tom Riddle, is their similarities, not their differences. Harry knows Tom because he knows himself, and imo, this desperation to make Harry as unlike Tom as possible is holding us back from some truly great exploration of their relationship.
Not everything needs to be opposites, just because Tom is bad doesn't mean Harry is incapable of murder or lying or torture. He shows us in canon he is capable of all that without any remorse. Two characters can have similar traits that present differently. They can both lie and be suspicious and clever at the same time. In fact, that increases the suspense and tension between them!
Honestly, I suspect this unspoken rule of opposites is heterosexual in origin. But for the record, Harry is not whatever Tom isn't, and neither is Tom simply what Harry lacks, they are complex characters with many shared traits and behaviours (deceitful, suspicious, resourceful, intelligent, stubborn).
I will grant that it is easier to write them as fundamentally unlike each other in any way, perhaps that's why it's done so much or perhaps its to give them something to fight about. But there is more than enough conflict to mine in their canon relationship, there is no need to make them polar opposites in order to give them something to argue about. Please step out of the black and white box. There is a garden full of nuance and complexity for you to explore.


















