In these fanfics, a likely theme is the exploration of family. Buffy and Spike are an unlikely pair, and having a captured baby in the mix forces them to deal with the idea of family in a new way. They might have to work together like a makeshift family to care for the baby. Also, the theme of sacrifice could be present. They may have to sacrifice their own wants or safety to ensure the baby's well - being.
I'm not sure of specific 'Buffy and Spike captured baby' fanfics off - hand. You could try searching on fanfic - specific websites like Archive of Our Own. They have a large collection of Buffy - the - Vampire - Slayer fanfics, and you might be able to find ones related to this rather unique scenario there.
I don't think there would be reviews for 'Buffy Spike sperm baby' fanfics. Fanfic reviews are usually for works that have some sort of value in terms of storytelling, character development, or exploring the Buffyverse in a meaningful way. This concept seems more like a shock - value or very niche idea that doesn't really fit into what reviewers would typically look for. Instead, reviews are more likely to be for fanfics that build on the established relationships between Buffy, Spike, and the other characters in a more positive and relatable manner.
The idea of a 'Buffy Spike sperm baby' fanfic is quite out there. Most Buffy fanfic communities focus on the characters' development, their battles against evil, and their complex relationships. For example, there are many fanfics that deal with how Buffy and Spike's relationship evolved over time, from enemies to something more. But the specific concept you mentioned is not a common or widely - promoted one within the Buffy fanfic world.
One popular Buffy and Spike baby fanfiction might be 'The New Beginning'. It often explores how Buffy and Spike deal with the challenges of having a baby in their complex world. Another could be 'Baby Steps' which delves into the emotional aspects of their new family dynamic.
Love and family are common themes. The stories often revolve around how Spike and Buffy's love for each other is strengthened by their love for their child. It's about building a family in the midst of their dangerous and chaotic world.
Buffy's relationship with Spike in the comics varies. Sometimes they have significant interactions and may even be romantically involved, but it's not a constant throughout all the comic series.
Another theme is the battle between good and evil within Spike. Given that he's a vampire, there's always that struggle, and Buffy's influence on his choices is a big part of many fanfics. For example, some fanfics might show how Spike's love for Buffy makes him question his vampiric nature and strive to be more 'human' in his actions.
One common theme is redemption. Spike's journey towards redemption and how Buffy fits into that is often explored. Another is the idea of forbidden love, as their relationship has always had elements of being something not quite accepted. Also, the theme of sacrifice comes up a lot, like one of them sacrificing for the other's well - being or for the greater good.