Well, in the Guardians of the Galaxy comics, Ego's fate is sealed and he indeed passes away. This event has major implications for the story and the characters involved.
Themes like love and friendship are also present. Love can be in the form of Ego's love for his son Peter, albeit in a very twisted way in the movie, but fan fictions can explore a more healthy form of that love. Friendship is about how the Guardians might interact with Ego if he were to change or if they had to work with him. Another theme is the concept of the greater good. How Ego's actions, whether good or bad, affect the overall well - being of the galaxy is often explored in these fan fictions.
Sure. One great piece of Ego Guardians of the Galaxy fan fiction is 'Ego's Redemption' on FanFiction.net. It delves deep into Ego's character and his possible change of heart after his encounter with the Guardians. Another interesting one is 'The Lost Tales of Ego' which explores some of the untold stories about Ego before the events in the movie.
The Guardians of the Galaxy comics are known for their humor. The combination of the characters' personalities and the creative storylines contribute to the funny aspect. Some issues are funnier than others, but overall, they have a good dose of comedy.