In some fanfics, Bella might avoid any physical contact that could lead to intimacy. For example, she quickly steps back when someone tries to get too close.
The author may show her hatred through her internal thoughts. Bella could be constantly thinking about how much she dislikes the idea of being close to someone in an intimate way, and these thoughts are shared with the readers.
It could be shown through their interactions. For example, Laurel might give Felicity cold glares or make snide remarks whenever they are in the same room. This is a simple yet effective way to convey her hatred in the fanfic.
Often, it's shown through his internal thoughts. The writer might describe Harry having angry and bitter thoughts about his parents when he's alone, like constantly thinking about how they left him to face so many difficulties. For example, he may think 'My parents left me to deal with Voldemort, they didn't care.'
Well, it could be that in the fanfic's storyline, Bella has had some bad experiences in the past related to intimacy. Maybe she was betrayed or hurt, which made her develop this hatred.
Often, the Justice League's hatred for Batman in fanfiction is demonstrated by their actions. They might exclude him from important missions or decisions. For instance, they could form a subgroup within the league and intentionally leave Batman out, showing that they don't want him involved. This can also be seen in the way they interact with his ideas. They may quickly dismiss any suggestions he makes without proper consideration just because of their dislike for him. And sometimes, they may even plot against him in the fanfiction, trying to undermine his influence within the Justice League.
His thoughts are also used to portray his hatred. The author might write from Harry's perspective, and we can see his negative thoughts about people. He could be constantly thinking about how everyone is out for themselves or how no one really understands his pain, which then colors his view of everyone around him.
It's often shown as a very intense and consuming force. Characters filled with this power might have a dark aura around them in the fanfiction. Their eyes could glow with a menacing look, signifying the 'Power of Hatred' within.
Often through his internal thoughts. The fanfiction might describe Luke seething with anger whenever he thinks of Vader. For example, in some stories, when Luke is meditating, his thoughts are constantly interrupted by visions of Vader and his past actions, and he can't focus because of his hatred.
The way Sebastian interacts with other characters in relation to Ciel can also show his hatred. He could be overly critical of Ciel in front of others or even try to undermine Ciel's authority subtly.
Often, it's portrayed with a great deal of passion. The spring scenery, like the blossoming trees and warm breeze, is described to enhance the mood.
Often, it's shown through her body language. For instance, she might flinch when he makes sudden moves or comes too close. In some fanfictions, she avoids being alone with him, which is a clear sign of her fear.