Korra would likely be very cautious at first. She's used to dealing with powerful opponents, but Hollow Ichigo's otherworldly nature would be something new. She might try to communicate with him, but if he showed aggression, she'd be ready to fight. Asami would probably be more strategic, trying to figure out his weaknesses. Mako and Bolin would be a bit more intimidated. Mako might use his lightning - bending as a first line of defense, while Bolin would be thinking of ways to use his earth - bending to either trap or slow down Hollow Ichigo.
There's a fanfic called 'Gabimaru and Sagiri: The Unlikely Alliance'. In this one, they start off as reluctant partners but gradually form a deep connection. The author does an amazing job of showing Gabimaru's protective side towards Sagiri and how Sagiri comes to respect Gabimaru's skills and determination. It has some really intense and emotional scenes that make it a great read.
Well, there are also those characters who might be a bit shocked or confused. Take Levi from Attack on Titan. He's a very serious and no - nonsense type of character. If he were to read some of the fanfic about him that deviated too much from his own self - perception, like being made into a comical or overly emotional character in the fanfic, he might be taken aback at first. But then he might also realize it's just a different interpretation and not take it too seriously.
Fate/stay night has four comics:
Fate/Stay Night (2007)
Fate/Stay Night: Heaven's Feel (2009)
Fate/Stay Night: Heaven's Feel II (2010)
Fate/Zero (2011)
In addition, there was a rumored work called Fate/Hollow Ataraxia(2013), which was a derivative work of Fate/Stay Night.
Characterization is key. A good Gabimaru x Sagiri fanfic should accurately portray their personalities. Gabimaru is tough yet has a soft side, and Sagiri is strong - willed and determined. If the fanfic can show how they complement each other, it's great. For example, Gabimaru's combat skills and Sagiri's strategic mind working together.
A common theme is the exploration of their relationship growth. Since they come from different backgrounds, fanfics often show how they overcome differences.