Not long after copperSteampunk/Karkat and xenoBiologist/John (hereafter known only as Karkat and John) experienced some time shenanigans that short-circuited the best part of a sweep so that they and their newborn son woke up on the same day *twice* (meaning that, from everybody else' perspective, young Kellen was suddenly two Earth years old), some even more bizzare temporal weirdness occured.
It was a fairly normal night in the Hornpile. There were two Karkats around (the other being unseenHatered) and the day had been busy with visits from speaking ponies and their friendly wingless dragon, shapeshifting robots (in disguise!) and Mituna's inevitable incomprehensibility. The gang were winding down for the evening when suddenly, another newcomer arrived.
The young visitor turned out to be Kellen from some sweeps in the future and he claimed to have visited "just for shits and giggles". He met many of his 'aunts' and 'uncles' in the full bloom of their youth and asked them politely not to tell his mother (John) that he there. Karkat sat back through most of the visit, and Kellen seemed not too bothered by this. Nobody really took any notice of this detail, so wrapped up were they in cracking jokes and getting a sneak preview of how Kellen would turn out. Besides, he must see Karkat all the damn time.
It turned out that Kellen had used a time machine on his future Hornpile to reach this timeframe against the express word of future John (quite a prudent decision on John's part. Time travel is a tricky and potentially dangerous proposition in the best of circumstances, on the Hornpile...) Eventually however, 'our' John found out, and was wheedled into promising not to punish the boy in the future (stay with me). This, however, was only the start of the family drama.
When Kellen's mother from his own time finally caught up to him (*very* late in the evening) having used the time machine himself, he seemed very hesitent and almost afraid to be there. Then ensued a lot of questioning about precisely why he seemed so out of sorts. Future John dodged and danced around the issue as best he could, trying to get Kellen home to his rightful timeframe, and by all accounts avoided directly telling anyone. His behaviour spoke volumes, however.
The parting was tearful, Kellen went from one family friend to another, exchanging goodbyes and best wishes, grown Trolls were brought to open weeping for reasons no-one could quite put their finger on... until it clicked that future John had avoided *Karkat*, right until the very end. In a moment straight out of romantic drama, future John embraced Karkat for what would be the last time (in his personal chronology) and warned our John and Karkat not to "grow up too fast". Everyone but Karkat had finally put the pieces together by the time final farewells were exchanged and the two visitors left for their home. Kellen had come back out of a desperate wish to see his father. By their time, Karkat would be *dead*. Few reacted well to this epiphany, stutteringLancer/Tavros (admittedly drunk by this stage) broke down into tears, John tried his best to hold together a 'we don't know and we don't need to know' front, stratosChatter/Morull told Karkat "Not on my fucking watch, don't you *dare*!", and Karkat himself just got more and more confused and frustrated until eventually he could take it no more and gave Morull a direct order to tell him what was going on.
All things considered, he took the news better than anyone else.
Morull, meanwhile, opened himself fully to his Muse and began furiously working on theoretical ways to ensure Karkat's survival in their own timeline. He was sure that, with the help of corpseCommunion/Feferi, Karkat could and indeed must be saved. Gene therapy was brought up and persued alongside more conventional 'time-buying' measures like fresh air, healthy sleep, regular exercise, green vegetables and clean living. Karkat agreed mostly to give Kellen (who would likely suffer the same shortness of lifespan) a fighting chance when his time came. Without a fully operational genelab and Ectobiology suite (both damaged by the ravages of Paradox space and unpowered in any case), however, the project was simply impossible. Now the whole Hornpile must deal either with a major biotechnological challenge that could sink pre-destruction *governments* on a shoestring, or the inevitable decline and death of one of it's founder members, followed eventually by the first flame of renewed life in both Trolls and Humans...
...sometimes it really *sucks* being among the last of your kind.
(additional:Little Kellen got his ears pierced during all the kerfuffle. Sometimes the Hornpile get's *really* strange)