Growing Pains (Not related to that other show
,) is a grimdark story that instead of killing off characters in gruesome ways or have a really dark setting, actually has a deep story and deals with the emotions of the mane 6 and the others instead of killing them, and all of the death so far is only with OC's so there's no fear of your favourite character dying.
There are two shippings
in this story which is Fluttershy/Twilight which is one-sided on Fluttershy's end, and Twilight/Rainbow Dash, but they don't affect the story that much so far, and with Twilight and Rainbow Dash it's mostly the friendship kind so it shouldn't bother you that much if shipping is not your taste. The fanfiction is so good that I'm surprised that no one has made a Tv Tropes page on it yet since it has 19 chapters and 204,910 words so far and is rated 5 stars on Equestria Daily, so that should be good enough to get its own page. So if you want a dark but not too dark adventure fanfiction of mlp:fim to read, than I highly recommend this.