It could. Karkat calls her autistic once but that could have just been him being a jerk. Nepeta being autistic is not 100% canon confirmed.

Not canonically

Dirky boy definitely has something, mad Depression for sure. I’ve seen arguments for him having NPD.  But  Dave doesn’t really shown signs of that. He’s got more of a depression fueled inferiority complex.

there was no DEAD text that accompanies most deaths so it was likely he was only at death’s door and Fef healed him

John was angry boy, Gamzee and Caliborn were taunting him cuz they’re jerks

Well I mean, he likely died in the GAME OVER timeline. He was on Dave’s planet when it got all smashed up.

He could means like different? He could also be referencing illnesses as in Rose’s predisposition to addiction could have been passed on genetically from Roxy, Dave’s issues seem more environmentally based but he could also have had an underlying  mental condition that he inherited from Dirk.

But knowing Dave he was probably just making a joke about how parents are the reason for everything that’s wrong with their kids.

A: Karkat being a mutant lime blood isn’t canon

B: He kinda did with Gamzee

4+1+3=8. 8 is the atomic number of Oxygen. Oxygen is why you breath. John is a Breath player. Throughout Act 5 Act 2 John had a flirtation thing with Vriska. Vriska. Do you  see it? I’ll say it again: Vriska. Still didn’t catch it? Sound it out with me: Vri. Ska. That’s right. Ska. As in Skaia, the governing force behind the story’s universe. But that’s not really true now is it? We all know Andrew Hussie is the real governing force of the tale. What do we know about Andrew Hussie, that’s it, he is attracted to Vriska. And who is Vriska attracted to at one point? Tavros. The symbol Tavros wears on his shirt is that of the Taurus constellation. Taurus is only one letter away from Tauros as in the Pokemon. Tauros has three tails. Three. Three is how many sides a triangle has. A triangle with an eye in the center is the symbol used by the Illuminati. Eye. Doc Scratch has no eyes. Doc Scratch is an excellent host. Newgrounds hosted [S] Cascade, but the site crashed on its release. Know what else crashed? Three planes on the date September 11th, 2001. One flight did not crash but landed safely. The president on that date was George W. Bush.  George W. Bush was the United State’s 43rd president. Did you catch that? He was the 43rd president and 1 flight did not crash into its intended target.

413 confirmed Bush did 9/11