There are quite a few. For example, 'Gaster's Unraveled Story in the Reader's Eyes' is a fanfic that tries to view Gaster from the perspective of the reader. It has a lot of in - depth analysis of his character. Then there's 'Gaster: The Reader - Centric Adventure' which is centered around the reader's experiences in Gaster's world, full of twists and turns.
One common theme is mystery. Gaster is often a mysterious character in the original source, and fanfics usually keep that element. They explore how the reader tries to understand Gaster.
There's also 'Gaster's Encounter'. This fanfic focuses on how the reader stumbles upon Gaster in a rather unexpected situation. It's filled with a lot of emotional moments as the relationship between them gradually develops. The character development in this one is quite engaging.
First, you should research about Gaster. Know his characteristics, backstory as much as possible. Then, think about how you want the reader to interact with him. For instance, are they friends, or is there a more mysterious relationship? After that, start with an interesting opening scene that draws the reader in.
Well, a major theme is the exploration of the unknown. Gaster's nature and his past are often shrouded in mystery in the original source, so in fanfiction, the reader and Gaster might embark on a journey to discover things together. Also, the theme of redemption can be present. Gaster may have some past mistakes or regrets, and the relationship with the reader could be a part of his path to redemption. Additionally, there can be a theme of power imbalance at times, as Gaster might have more knowledge or power, and how the reader deals with that in the relationship is explored.
A 'gaster lemon fanfic' is probably a piece of fan - made literature. Gaster is often a mysterious character in certain fandoms. In this fanfic, the 'lemon' aspect might imply a more saucy or exciting narrative. It could be that the author is exploring Gaster's character in a more adult - oriented way, but it could also be a more innocent, yet still 'lemony' in the sense of being a bit edgy or different, exploration of his relationships with other characters, perhaps delving into uncharted areas of his fictional existence.
A 'blind gaster fanfic' could be a fan - created fictional story related to the character Gaster who is blind in the context of that particular fanfic. It might explore his experiences, relationships, or adventures while dealing with his blindness.
Power and knowledge are also common themes. Gaster is often depicted as having a great deal of knowledge, and his experiments might be related to power in some way. Fanfics explore how this knowledge and power can be both a blessing and a curse. They might also show how other characters react to Gaster's power and knowledge, whether it's with fear, envy, or admiration. In addition, some fanfics have a theme of redemption. Since Gaster's actions may have caused some chaos or harm, the fanfic could be about him trying to make amends in some way, either directly or through the actions of others he has influenced.
A sense of otherworldliness is common too. Since Gaster Sans is from a rather strange and unique universe, the fanfictions often play with the idea of the reader being in a very different, almost alien world. This can lead to themes of adjustment, as the reader tries to fit into this new world while being in a relationship with Gaster Sans.
The reader might interact through dialogue. They could ask questions about the different AUs and the characters' backstories. For instance, asking Sans about his life in his particular AU.