I don’t know... Toland the Shattered was pretty messed up...

I wouldn't say that their stories are any more darker than the others (not exponentially so, at least). It's just that they have more stories about them. There's plenty of stories about the other classes that are pretty messed up, just not as numerous as the Hunter ones. [spoiler] There's the one about Felwinter (Warlock) killing a proto-guardian and destroying his ghost, then lying about it to the other Iron Lords, saying he convinced him to give up his territory willingly. There's Kabr (Titan) who got stranded in the Vault of Glass and slowly assimilated into the Vex collective (and who also used his dead Ghost and dwindling light to make the Relic Shield). Eriana-3 (Warlock) who, after torturing a Hive Wizard, was shown a vision of her good friend Wei Ning (Titan) slaughtered on Crota's blade then, in pursuit of revenge confronted Crota in his throne (most likely alone) and was killed. Toland (Warlock) is trapped in the space between green-black suns beyond Crota's god star going insane, screaming out for his friend Osiris. Saint-14 (Titan) was lost in the Vex network trying to bring back his close friend (also) Osiris when he found out he was exiled from the City. Taeko-3 (Warlock) and her team were all stripped of their light and turned into power crystals (as we all know, she willingly sacrificed herself so we could stop the Hive ritual). Asher Mir (Warlock) lost both his fireteam and his arm to horrendous experiments done by the hands of Brakion (seriously, read about this if you haven't. It's heartbreaking and reveals a lot as to why Asher is an ass most of the time, trying to keep others at an arms length so he doesn't have to experience such a loss again). Arguably the most messed up story in Destiny is of the Titan, Rezyl Azzir, who was corrupted by a Hive witch and turned into the worst human-scourge the frontiers have ever seen; Dredgen Yor. [/spoiler] Hunters also spend most their time out in the wild. You're more likely to drown when you're swimming, same as you're more likely to experience seriously messed up shit when you're poking your head around in every bottomless chasm filled to the brim with countless unspeakable horrors with a startlingly high inclination to murder both you and everything you love with a rusty spoon. But yeah, I don't think the Titans and Warlocks are gonna get off scot-free in Forsaken. Cayde is just the beginning...

Saint -14? Dredgen Yor?

There are dark stories from all 3 classes. Hunters might have the most blatant examples, such as Eris or Dredgen, but there are plenty of awful deaths and other tragedies from all classes. [spoiler]Although, the most horrific death I’ve seen was a hunter named Omar Agah. Read the Heart of Crota grimoire card unless you’re easily disturbed.[/spoiler]