Well, one way could be that the OC encounters the Doctor during a particularly dangerous adventure and gets hit with some sort of memory-erasing energy. This could lead to them relying on the Doctor and the companions to piece together their past.
You could start by having the OC wake up with no memory in a strange place related to Doctor Who's universe. Maybe they were involved in a time-travel accident or experiment gone wrong.
You could start by having the OC wake up with no memory in a strange place related to a Doctor Who adventure. Maybe they were caught in a time vortex or something. That creates mystery and adventure right away.
Common themes could include the struggle to fit in while dealing with memory loss, uncovering hidden secrets about the character's past, and forming new relationships that help in the recovery process. Also, themes of identity and purpose frequently surface.
One could be the OC trying to piece together their lost memories while encountering various adventures with the Doctor. This creates a sense of mystery and keeps the readers engaged.
You could have a situation where the OC believes that rectal temperature is the ultimate measure of a character's 'coolness'. So, they go around taking everyone's rectal temperature to see who is the 'coolest' in the fanfiction world. This absurd concept can create a lot of comical dialogue and interactions between characters.
One way could be to create a unique backstory for the OC male Sayain. Maybe he crash - landed on a Mass Effect planet and has to adapt to the new technology and species. His Sayain powers, like super strength and quick reflexes, could make him a formidable ally or a feared enemy in the Mass Effect universe.
Perhaps the OC is a descendant of a long - lost wizarding family who was exiled due to their interest in dark arts - like gaming. They come to Hogwarts to seek redemption or revenge. Their dark gamer traits could include a fascination with dangerous magical challenges and a disregard for some of the traditional Hogwarts rules, which would lead to conflicts and adventures.
Well, first think about the kind of threat or adventure the OC is involved in. Maybe it's a dangerous alien encounter or a malfunctioning time machine incident. Then, describe the injury and its immediate impact on the story and other characters in a way that keeps the readers engaged.
First off, for a compelling mutant OC in Doctor Who fanfiction, focus on their motivations and how they evolve throughout the story. Make their powers both interesting and have limitations. Also, make sure they fit well within the Doctor Who world's rules and logic.
The key to including a male OC is to make him interact with the main cast in meaningful ways. For example, he could have a shared interest or a conflict with them. You can also build his story arc to parallel or contrast with the main plotlines of How I Met Your Mother. This way, he becomes an integral part of the fanfiction rather than just an addition.
You can also check websites specifically dedicated to finding beta readers for various types of fanfiction. Some of them have sections for specific fandoms like Doctor Who. It might take a bit of searching, but you're likely to find someone suitable eventually.