Well, popularity is relative. In some fanfiction communities, they might be quite popular because they offer a different take on the well - known Death Battle concept. People who are interested in exploring the characters' relationships in a more...shall we say, 'intense' way might be drawn to these. But in the broader context of all fanfiction, they are probably not as well - known or widely read as other types.
Well, reactions to RWBY Death Battle fanfiction can vary greatly. Some might be excited about the unique battles and character match - ups depicted in the fanfiction. It could bring out new perspectives on the RWBY characters' abilities and how they would fare against each other in different scenarios. For example, seeing how Ruby's speed and scythe skills compare to another character's powers can be really thrilling.
One of the most popular death battle scenarios in One Piece fanfiction is the clash between the Straw Hats and the Blackbeard Pirates. It's exciting because both groups have strong and diverse members. Another popular one is a duel between Ace and Akainu re - imagined in a different way than in the original story. Also, battles between the yonko like Kaido and Big Mom are often written in fanfiction as death battles.