You are now the prankster kid, who apparently should have been having his beauty sleep. You woke earlier than usual so you could put together a master prank for everyone, since you have to prank everyone at least once a year just to prove you are still the same, marvellous John Egbert and always will be. Only, you plan took a turn and ended up ease dropping on Dave and Karkat's conversation in the camper.
You don't know how to react. Karkat tried to kill himself. Kill. Himself. You had no idea he was depressed. You thought that he was just his plain grumpy self, who didn't want to be bothered.
You know that people are cutting him off, writing him out of their lives, and you are one of those people, you hate to admit. But there's a reason. It's wasn't the fact he was T-human or a mutant, he was still Karkat, their friend, it was the fact that he's mutancy could eventually kill him – whether by the hands of another troll or growing ill and dying young.
That was the thing, even though Karkat's candy-red blood and his lifespan is equivalent to a human's, he still had to deal with maturation like other T-humans and trolls. Maturation was different for them than it was for humans, instead of it happening through the years known as adolescence; they went through a week to a month long process. You know these facts from Rose who dates Kanaya who knows plenty about trolls and T-humans.
When maturation occurs for them, their skin gets smother but stronger, their hair gains a little color that is similar to their blood, they grow taller – you doubt that Karkat will though – their teeth get sharper, muscles get stronger, and agility increase, as well as stamina. Unlike trolls, T-humans get abilities once maturation kicks in (if Vriska were T-human she wouldn't have her physic abilities until then – also the game let abilities that they already had before playing the game exist in this universe, though there are some exceptions like Kanaya being a rainbowdrinker). When their eyes change color it shows they will start they maturation. Basically, trolls and T-humans become more badass as they grow, unlike humans that stay their same boring selves.
Karkat's eyes are now crimson, meaning maturation will kick in soon for him. However, there is a price for being a mutant, that both Signless and Kankri were lucky to escape it. Karkat on the other hand may not have as much luck. His maturation could backfire and cause him to end up on his deathbed. Signless and Kankri are fairly anxious about this and keep a close eye on Karkat for any signs that could tell them whether he'll do all right. He'll end up growing ill, and get weak, and could die. Kankri nearly died, but he pulled through – Karkat wasn't around when it happened to him.
In result, you all are trying to push away from Karkat, because if he dies, you all will suffer greatly. Karkat may not seem to be the glue that holds them together anymore, but he still is, there's just no replacing him and the memories you have of him. He dies, this group of friends will struggle to stay together. You're all just preparing yourselves for the inevitable, though you all know, deep down inside, that it'll hurt you all no matter what. You and Vriska wanted to see if you could perhaps manage to give him good luck so he could live – yes, Vriska cares, she's not as cold and cruel as she was back then.
You all, one by one, realised that Karkat could be lost, just when you thought you'd all live together happily. Of course the universe wasn't finished proving you all wrong and tormenting Karkat. Dave was the only one really left that wasn't truly aware, but you knew that he noticed something wasn't right. Still he stays by Karkat, even though you all know if anyone will be hurt if Karkat dies, it's going to be Dave. He will be crushed, and then a domino affect will happen.
You realise that pushing Karkat away will not solve the problem, only make it worse. When he dies, you'll all wonder 'why didn't I do something' only for it to be too late. If anything, you should be acting like Dave, like a supportive friend, like Karkat won't die, like everything will be fine even if it ends badly. The fact that you all pushed Karkat away, except Dave, had led to Karkat attempting to end his life short, was heart wrenchingly painful. Karkat shouldn't have done that; he needs to live his life to the fullest. But how can he do that if his friends push him away because they believe he'll die?
You make a decision to get the gang together while Dave and Karkat strife, even though it's 6:35 in the goddamn morning, never again will you wake up this early.
The others will be pissed at you for waking them up, but this is serious shit and serious shit needs to be taken seriously. You need to change how things are, now.