Jadekat

Jadekat is the het ship between Jade Harley and Karkat Vantas from the Homestuck fandom.

Canon
Jade and Karkat start off both strongly disliking each other, and Karkat constantly harassing Jade on the internet. Due to the way Karkat's chat application works, Jade is caught in the middle of arguments between him and his past self. Jade, usually being quite cheerful, loses her cool at this point and freaks out at both Karkats. Eventually Karkat apologizes to her, and their relationship gets much better from there. Jade creates a password system so that she can tell which point in the timeline the Karkat she's talking to is at. This greatly frustrates Karkat, but Kanaya suggests he likes Jade (possibly romantically) because she gives him a reason to be angry. Karkat is shown at one point imagining Jade and her alternate self kissing, implying he has some level of physical attraction to her. Karkat seems to still be fond of Jade after they separate, using one of her passwords to open a door; when asked about it, he says it's "JUST SOMETHING THAT REMINDS [him] OF AN OLD FRIEND". On Earth C, they are shown ruling the Troll Kingdom together aside Dave.

Post-Canon
In the Candy Route of the Homestuck Epilogues, Jade and Karkat are living together with Dave. Jade pressures Karkat and Dave into being into a triad relationship with her, which both are clearly not comfortable with. Karkat ends up leaving the relationship, both due to Jade's actions and the human-troll political tension. He later shows up at Dave and Jade's wedding, now the leader of the troll rebellion and much more distant with both. They appear to have severed ties after this.

Fanon
Jadekat was a very popular ship in the early days of the Homestuck fandom, and is still somewhat prominent now. Their dynamic is widely enjoyed, with fans pointing out that Jade keeps Karkat's behavior in check and Karkat is kinder to Jade than he is to others. The ship lost popularity after the way they were portrayed in the (dubiously canon) Epilogues, as did Davejade. Those who still like the ship have mostly elected to ignore their depiction there, viewing it as out of character. Jadekat is often paired with Spider8reath, Rosemary, and/or Daverezi, due to them being beta kid x patron troll ships. It is rivaled by the more popular Davekat and Davejade, although the OT3 Davejadekat is also popular.