It could be about a character played by Sam Witwer having his own adventure in the Star Wars universe. Maybe he's a smuggler like Han Solo, exploring uncharted regions and getting into all sorts of trouble with the Empire or other factions.
I'd recommend 'Sam's Journey into the Vampire Realm'. This fanfiction details Sam's accidental entry into the vampire realm and his struggle to find his way back home while also dealing with the various vampires he meets. It's a great story that combines adventure and the allure of the vampire genre. There's also 'Vampire Love and Sam' which delves into a romantic relationship between Sam and a vampire, exploring the challenges they face.
In Sam is a vampire fanfiction, the theme of forbidden love is quite common. If Sam gets involved with a vampire, their relationship is likely to be seen as taboo. Additionally, the search for identity can be a theme. Sam may be questioning who he is in relation to this new vampire - filled world he has entered, and how he fits into it all.
One possible analysis could be that it might explore the darker sides of the characters Dean and Sam in a vampire - themed scenario. Maybe it delves into how they deal with the vampiric nature, whether they resist it or succumb to it. It could also be about their relationship dynamic changing due to the vampiric influence.
One common theme could be the struggle between good and evil within the characters. Even as vampires, Dean and Sam might still have remnants of their former moral compasses. Another theme could be isolation, as they may be shunned by their human friends and allies due to their vampiric nature.
In fanfics, all kinds of scenarios are possible. Just because it's written doesn't mean it adheres to the original canon. Maybe the author wanted to explore a unique relationship dynamic through this pregnancy plot. However, without reading it, it's hard to say more about it.
I don't know who Sam is without reading the 'kings fund sam's story'. Sam could be a patient, a researcher, a staff member or someone else related to the Kings Fund.
Sam could be just an ordinary guy who loves exploring the woods. He might be a nature enthusiast who spends his free time in the forest, and one day he just happens to come across Bella.
Sam Evans in 'sam evans first time fiction' is a mystery. He could be an aspiring writer who is making his first foray into fiction writing. Or he could be a fictional character in the story, with his own unique backstory and personality. We just need more information to be certain.