These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The fake Gennai. What he does to Mimi is quite possibly the most disturbing act of callousness in the entire franchise (canon included).
Daemon definitely counts as well. There is nothing he cares about more than inflicting as much suffering as possible, and he is perfectly willing to slaughter thousands including a seven year old girl in order to get what he wants.
Cult Classic: Tamers Forever could be seen as a Cult Classic among Digimon fan fiction circles. It's not as well known as some other Digifics out there, But it is absolutely adored by those who have read it. (Just look at the reviews Silent Sorrow recieved)
Although Tamers Forever is an undoubtedly fun and surprisingly well written series, it's still fairly average, until "Forget the Y2K, This is Madness!!", whereupon the series adopts a quality of story-telling that is on par if not better than that of professional authors.
Iron Woobie: Takato could be the poster boy for this trope, the amount of physical and mental torment he suffers through over the course of the series must be seen to be believed, but he takes it all on with a smile on his face. Seriously, the kid is a walking talking Crowning Moment of Awesome.
Jerkass Woobie: Rika, oh dear god, RIKA!! She is self-centered and mean with an outrageous competitive streak. But it is physically impossible to read Silent Sorrow and not have your heart ache for her after seeing what the author puts her through.
Laughably Evil: Even if he's not technically evil, there is no denying that Chaos is absolutely hilarious.
The Fake Gennai crosses over when he kidnaps Mimi's unborn child
The Woobie: You can't help but feel sorry for Pauline once it's revealed that she desperately loves Takeru but she can never be with him, because she's just a computer program.
Wangst An in-universe example. Takeru calls himself out on this:
I wish we could switch places. If my death could save the world, I'd gladly give my life. I have nothing left here. Not anymore. But you're still so young. You could be so happy…you would make her so happy. But I can't. You're the one who has to die, and I have to stay and live this empty, meaningless life. And I'm a bastard for feeling sorry for me when you're the one who I should worry the most for. You're the one who is going to die, but my heart cries for my living. I'm worthless.