Yes, it is quite popular. There are a number of fans who like to combine the two concepts. They love to see how the heroes and villains of Overwatch would fare in the intense battles characteristic of Death Battle. There are various online platforms where such fanfiction is shared and discussed, which shows that there is a significant audience for it.
Typically, it might feature the characters from strq observing the intense battles in Death Battle. There could be a lot of reaction elements, like shock, excitement or analysis from the strq characters.
Yes, it likely exists. There are fanfiction for all sorts of combinations in the world of fandoms. Since both Spiderman and Death Battle are popular topics, it's very possible that someone has written fanfiction that combines the two, and Spiderman could be depicted as reading or being involved with such fanfiction within that fictional story.
There are often fanfictions that involve crossovers in 'watches death battle' scenarios. Imagine a battle between a superhero from the DC universe and a powerful anime character. These crossovers can lead to really exciting and unexpected plot twists as the different power systems interact.
Maybe Spiderman gets some new combat ideas. He could see some unique fighting styles in the Death Battle fanfiction and incorporate them into his own superhero battles.
Obviously, Sonic himself is extremely popular. He's the main character, after all. Tails also often makes an appearance as Sonic's sidekick. Knuckles is another popular one, with his strength and connection to the Chaos Emeralds. And then there are the villains like Dr. Eggman who are frequently part of the death battle scenarios in these fanfictions.
One popular one might be those that focus on unique character interactions during the 'death battle' scenarios in the Bleach universe. For example, a story where Ichigo has an unexpected alliance during a battle.
There are also some Bleach - specific fan forums where fans might share their own 'bleach watches death battle' fanfictions. These forums can be a great place to find unique and less - known stories that might not be on the bigger platforms. However, you need to be careful as the quality can vary greatly.
He could become interested in the characters from Death Battle that he hadn't known much about before. The fanfiction might introduce him to new storylines and relationships within the Death Battle universe. This could potentially influence his view of the overall concept of Death Battle, perhaps making him more or less interested in it depending on the quality and nature of the fanfiction he reads.