Well, it could be about the characters from Homestuck somehow ending up in the Veggietales world. Maybe the Homestuck kids have to learn some of the moral lessons that Veggietales is known for. For example, they could help the Veggietales characters with a problem in their veggie - world, like saving the town from a giant cucumber - monster. And in return, the Veggietales characters might introduce the Homestuck kids to their simple and positive way of life.
I think John Egbert from Homestuck and Bob the Tomato from Veggietales would be really interesting. John is this really optimistic and kind of goofy character, and Bob is always so level - headed and full of wisdom. Their interactions could be really fun, like John trying to understand Bob's simple but profound view on life, and Bob trying to keep up with John's wild ideas.
A good plot could involve a villain from the Homestuck universe creating chaos in the Avengers' world. The Homestuck characters come to help, but there are misunderstandings at first between them and the Avengers. However, as they start to understand each other's powers and motives, they form a strong alliance to defeat the villain.
One common theme is the exploration of different cultures. In both Steven Universe and Homestuck, there are unique cultures. In crossovers, it's interesting to see how the Crystal Gems' way of life and values interact with the trolls' or the kids' in Homestuck. For example, the idea of friendship and loyalty is strong in Steven Universe, and it can be contrasted or combined with the relationships in Homestuck.
One idea could be that the characters from Homestuck end up in the Underground of Undertale. They might have to deal with the various monsters there while also trying to find a way back home. Maybe John Egbert could team up with Frisk and they use their unique abilities to overcome challenges like puzzles and battles.
John Egbert and Spider - Man could be an interesting pairing. John's ability to manipulate wind and his generally positive attitude could contrast well with Spider - Man's quippy and more street - level heroics.
Yes, there are quite a few. Some focus on character interactions, like how the Homestuck characters would interact with the RWBY teams in combat or in daily Beacon life. For example, a fanfic might have John Egbert sharing his adventures with Ruby Rose, and they could learn from each other's experiences in their respective strange worlds.
One challenge is getting the characterizations right. Homestuck has very distinct and complex characters, and when you cross them over with characters from another fandom, you need to make sure they all stay true to their original selves. Another is the world - building. Combining two different fictional worlds can be tricky to make it seem seamless.
One popular 'Steven Universe Homestuck Crossover Fanfic' is 'The Gemstuck Adventures'. It combines the unique worlds of Steven Universe and Homestuck in an interesting way. The characters from both universes interact in unexpected ways, like Steven meeting the trolls. Another one could be 'Fusion of Universes' which focuses on how the powers and concepts in both shows blend together.
Frisk and Dave Strider would be an interesting pairing. Frisk is all about kindness and determination in Undertale, while Dave is this cool, sarcastic guy from Homestuck. Their different personalities could lead to some really fun interactions, like Dave trying to be all cool while Frisk just goes about their business of being kind to everyone.