Looking at both stories in question, I can't but notice similair aspects from them:

Both characters are found with no memory of their past.

Both are the remains of a dark entity that was a threat to Equestira.

Both befriend a foal from their new home.

Both try (and in Sombra's case fail) to keep themselves from becoming what they once were.

Both are confronted by the Princesses who try to convince them not to follow their dark path and imprison them.

Am I the only one seeing this?

How did I not see that before? Also now that you have said it someones gonna make a story where Nyx and young sombra meet.

It never crossed my mind, but you have a good point.

What are you talking about..? If you don't mind me asking.

4292800 They are comparing the fanfic Past Sins with the Fiendship is Magic Comic detailing Sombra's origin, and yes I can see the similarities, though I think the story felt rushed, not really giving many compelling reasons as to why he turned bad. There are reasons, and they are to a point believable, but I feel it could have been so much more. If you want a truly heart-wrenching and believable (mostly) fall to evil in fantasy, look to Arthas, the Lich King in the Warcraft series, the Anti-King Arthur. Now that is something I wish Sombra's back-story could have been like (not word for word but somewhere along those themes), but hey for what we got it was OK.

I honestly don't see how the ending of Past Sins was bad, especially when I cannot find the reason on how tit was bad. Besides, it's better than the Tragedy stories. I hate dead hero stories with a passion.

4292952 You misunderstood. He was comparing the Fiendship is Magic comic #1 (Sombra's issue) to Past Sins and thought the issue's ending could make a similar possible bad ending for Nyx in Past Sins.

4293248 Oh! A bad ending for Nyx, not Past Sins ending being bad. OK, I get it now.

That is really interesting. But I think, Sombra was simply destinied to become that monster. He had no mother, because he was no pony.