As I mentioned before, Dee Dee could be a likely candidate. She's always getting into Dexter's business, and a pregnancy could add an interesting layer to her character. It could show a more serious and responsible side of her as she prepares to be a mother.
One possible plot could be that one of Dexter's female friends or a female character in the Dexter Laboratory world discovers she is pregnant. She might then turn to Dexter for help, thinking his scientific genius could assist in some way, like creating a device to monitor the baby's health in a unique way.
It could be Dexter's teacher. If she got pregnant, it would add an interesting layer to the school environment in the Dexter Laboratory. The students, including Dexter, might be curious and try to understand what's going on. And she could be dealing with all the normal pregnancy stuff while also trying to teach her students, which could lead to some comical and heartwarming situations.
One idea could be that one of Dexter's female relatives, like his sister Dee Dee, accidentally gets pregnant. This could lead to chaos in the laboratory as Dexter tries to figure out how to deal with the situation while also keeping his scientific experiments running. Maybe he creates some sort of device to help with her pregnancy symptoms or to keep her out of his lab during her mood swings.
Finding a specific 'raven and dexter pregnant fanfic' can be a bit of a challenge. It depends on the popularity of the characters within the fanfic community. Some smaller or more niche fandoms might not have as many fics on a particular topic. However, if these are characters from a well - known series, there could be a chance that someone has written a fic with that plot. Try reaching out to fanfic communities or forums dedicated to the source material to ask if anyone knows of such a fic.
Fanfiction.net could also be a source. Just use the search function and type in 'raven and dexter pregnant' to see if there are any relevant results. However, note that the quality and content can vary greatly on these platforms.
The Grim Reaper from 'The Grim Adventures of Billy & Mandy' could be an interesting addition. He could bring some dark humor and a different kind of magic to Dexter's world of science.
One idea could be Dexter crossing over with another smart character like Jimmy Neutron. They could compete in a science fair, leading to all kinds of wacky inventions and mishaps.
One great dexter x blossom fanfic is 'The Unlikely Bond'. It beautifully weaves their different personalities together in an engaging story. The author does a wonderful job of creating a believable relationship between the two characters.
Dexter and Dee Dee's relationship might become more cooperative. Since they are going to be siblings to the new baby, they might start to work together more often. For example, they could team up to decorate the baby's room. Instead of Dee Dee constantly barging into Dexter's lab, she might start to ask permission more politely because she realizes that Dexter is also stressed about the new baby coming.