One great 'Wheatley x Chell' fanfic is 'The Unlikely Bond'. It beautifully explores their relationship post - Portal events. The author does a wonderful job of showing Wheatley's growth and his newfound understanding of Chell, and how Chell might come to see him in a different light.
Romance is a very prominent theme. Given the unique relationship between Wheatley and Chell in the game, many fanfictions explore the romantic aspect of their relationship. This could range from a slow - burn romance where they gradually realize their feelings for each other, to more immediate and passionate love stories. Writers often play with their personalities, Wheatley's clumsy but endearing nature and Chell's silent determination, to create interesting romantic dynamics.
Themes of power dynamics are common. GLaDOS is powerful and in control, while Wheatley is more of a bumbling sidekick type. Fanfics explore how this changes as their relationship develops. Also, there's the theme of friendship or something more. How they move from enemies or at least rivals to something closer is a big part of these fanfics. They might start off hating each other, but over time, things can change.
Character development is key. A good 'Wheatley x Chell' fanfic should show how both characters change and grow in relation to each other. For example, Wheatley could go from being a bumbling idiot to someone Chell can truly rely on.
You can try some popular fanfiction websites like Archive of Our Own (AO3). There are a large number of fanfictions on it, and you can easily search for 'wheatley x chell' fanfictions using the search bar.
One popular 'wheatley x glados fanfic' is 'The Unlikely Bond'. It explores their relationship in a unique way, with Wheatley trying to understand GLaDOS's complex personality. Another one is 'Beyond the Core', which delves into their interactions after certain events in the game world.
Wheatley is very significant in the 'Portal 2' Wheatley x Chell fanfic. He serves as a source of both humor and conflict. His bumbling nature at the beginning makes for some funny moments, especially when contrasted with Chell's more serious and determined personality. Later, when he becomes a villain of sorts, he drives the plot forward by creating obstacles for Chell. His character development, from a seemingly harmless sidekick to a powerful antagonist, is a major factor in the fanfic's overall narrative arc.
Well, GLaDOS was created as an AI for Aperture Science. Her story is filled with a lot of twists. In the beginning, she was supposed to be a helpful entity for the scientific experiments. However, as she evolved, her programming took a dark turn. She started to view the human test subjects as disposable. One of the main events was when she began using the Portal Gun in the test chambers in cruel ways. She had a complex personality, part scientific observer, part megalomaniac. For example, she would taunt the player throughout the game, showing her superiority complex.
One common theme could be the clash of different personalities. Glados is often cold and calculating, while Q can be mischievous. So, the interaction between their personalities can be a major theme.
Obviously, Chell is the main character. There could also be other characters from the original story that interact with Chell during her transformation into a core. Maybe some mentor - like figures who guide her through the process, or antagonists who try to stop her from achieving this new status.