One common theme could be the struggle of dealing with the unexpected pregnancy. Given their complex relationship and the challenges they face in the Buffyverse, it adds an extra layer of drama. Another might be how their friends and allies react to the news.
Love is a very common theme. Since their relationship is so central to the Buffy and Angel story, in human fanfiction it often explores different aspects of their love, like how it might be different if they were just normal humans. For example, they might not have the same life - or - death stakes in their relationship.
One common theme is the struggle between good and evil. Since Buffy is a slayer and Angel has a vampire nature, they constantly battle against dark forces, and this is often explored in fanfiction. Another theme is love. Their love story, which is complex due to their different natures, is a central part in many stories.
One common theme is redemption. When they travel through time, they often get a chance to right past wrongs, like Angel getting a chance to save someone he couldn't in his original timeline. Another theme is the exploration of their relationship. Time travel allows the story to show how their relationship could have developed differently in different time periods. Also, the theme of fate vs. free will is common. They might try to change things in the past, but are constantly faced with the question of whether it's possible or if they are just following a set fate.
One common theme is the struggle between their love and the obstacles they face. Since Angel is a vampire, there's always the issue of his vampire nature conflicting with their relationship. Another theme is the intense emotions. Their first time is often depicted as a very passionate and emotional moment, filled with years of pent - up feelings.
One common theme is the struggle with their identities. Buffy is a slayer and Spike is a vampire, so having a baby challenges their usual roles. Another theme could be the reactions of their friends and enemies. Their friends might be shocked or supportive, while their enemies could see it as a weakness to exploit.
Love and sacrifice also play a big role. There could be a situation where Angelus has to make difficult choices to protect Buffy and the unborn child, or Buffy might have to sacrifice her slayer duties to some extent for the sake of the pregnancy. These themes of love, protection, and sacrifice are often central in such fanfictions.
One common theme could be the shock and adjustment. Given their relationship in the original series, the idea of them having a child is unexpected, so dealing with that shock is often explored. Another might be the protection of the unborn child, considering the dangerous world Buffy and Giles are a part of.
One common theme is the struggle between good and evil, especially with Angel and Angelus. Since Angel has this dark side in him, a lot of fanfics explore how he tries to keep Angelus at bay while also being with Buffy. Another theme is love and sacrifice. Buffy often has to sacrifice her own feelings for the greater good when it comes to Angel and Angelus.
Often, the theme of temptation is present. Maybe there's a new character in the fanfic that Buffy finds irresistible, which leads to her cheating. And also, the theme of guilt and self - discovery can be common. After cheating, Buffy might have to face her own actions and figure out who she really is.
Well, often there's the theme of the unexpected. Given their lives filled with fighting demons and all, pregnancy might be a very unexpected turn. Also, there could be themes related to their insecurities. Riley might worry about being a good father considering his own past and Buffy might worry about protecting the baby from all the evils around. And of course, there could be themes about their relationship evolving in new ways because of the pregnancy.