Definitely Ruby Rose. Since she's the main protagonist in RWBY, it's likely that Natsu would cross paths with her first. Their personalities are quite different, with Ruby being more innocent and Natsu being more brash, so their interactions would be interesting.
Well, it could be about Natsu finding himself in the RWBY universe and having to adapt to the different combat styles there. Maybe he teams up with the RWBY characters to fight a common enemy.
I'm not sure who exactly Natsu is just from 'natsu reads fanfiction'. It could be a normal person who just enjoys reading fan - made stories. Maybe it's a nickname for someone within a particular fan community.
In the 'natsu went mia in war fanfiction', Natsu is presumably a central or important character. He could be a hero - type figure who was expected to play a significant role in the war. It's possible that he has some special abilities or traits that made his presence crucial. Since he went MIA, the whole story might be about his friends or allies trying to find him or dealing with the aftermath of his disappearance. It could also be that Natsu is a character with a complex backstory, and his going missing in action is a key event that will unfold and reveal more about his past, his relationships, and the overall world of the fanfiction.
He could marry an original character created specifically for the fanfiction. This character could be a powerful mage from a far - off place who crosses paths with Natsu during one of his adventures.
In such fanfiction, Natsu might be depicted as more passionate and impulsive than in the original work. His fiery nature could be emphasized in a romantic or more intense context. Laxus, on the other hand, may be shown as more brooding and powerful. His strength and dominance could be a key part of the relationship dynamic in the fanfiction.
One of the senior and more experienced members of the guild. They have seen a lot and know how things should be done in the guild. If Natsu acts in a way that goes against their long - established ways, they would not hesitate to berate him.