Well, a common theme is the exploration of the baby's powers. Since the Doctor has his own set of extraordinary abilities and Rose has her own strength, fans like to imagine what kind of powers their baby might have. It could be something related to time manipulation or a special connection with alien species. Love is also a big theme. How the Doctor and Rose's love for each other is transferred to their love for the baby and how that love overcomes different obstacles in their lives.
One popular theme is the adventure aspect. Fans often write about the baby growing up in a world full of time - traveling and alien encounters, just like the Doctor and Rose had. Another theme is family. It could be about how the Doctor, Rose, and their baby form a unique family unit, dealing with the challenges of being part of different species. Also, the theme of protecting the baby from various threats, both from within their own universe and from other dimensions, is quite common in these fanfictions.
Some fanfictions focus on the baby's identity. Given the Doctor's complex nature as a Time Lord and Rose being a human, the baby's identity can be a really interesting theme. Will the baby be more Time Lord - like or take after Rose's human side more? And there's the theme of legacy. The Doctor has a long history and a big reputation in the universe. How will the baby carry on that legacy? These are all things that are often explored in tenth doctor and rose baby fanfiction.
Adventure is another theme. Since they travel through time and space together, many fanfics have them going on all sorts of exciting adventures, whether it's saving a planet or exploring a new era. It adds to the overall charm of their relationship as they face these challenges together.
A great idea for this fanfiction could be that Rose starts having dreams about their future child. These dreams could give them clues about the baby's purpose or the challenges they will face. The Doctor would be very interested in these dreams and try to analyze them scientifically.
In the fanfiction, Rose's pregnancy could be a catalyst for the Doctor to finally settle down in one place for a while. Maybe they find a peaceful planet where they can build a home and prepare for the arrival of the baby. Their friends from their adventures might come to visit and offer their support. It could also lead to some interesting cultural clashes as they combine their different upbringings and knowledge to raise the child.
Love is a very common theme. Their love for each other is what binds them as they face the new challenges of having a baby. It's shown in how they support each other through the difficult times.
Writers often start with the baby as a symbol of hope. As the story progresses, the baby might start to show curiosity, much like the Doctor. For example, reaching out to strange objects or showing an interest in the TARDIS. Then, as the baby grows, it could develop a sense of justice, similar to how Rose always stood up for what was right. Maybe the baby starts to question things around it, just as the Doctor is always full of questions.
A common plot in such fanfiction is a kiss that seals a promise. For example, the Tenth Doctor might promise Rose that he'll always be there for her, and the kiss is a physical manifestation of that promise. It can also be a kiss that occurs during a time-travel adventure. Maybe they are in a beautiful historical setting, and the moment just calls for a romantic kiss.
One popular one could be 'A New Beginning' where they start their married life on a new planet, facing all kinds of adventures together. It's full of their typical banter and sweet moments.
Another interesting one is 'Parallel Worlds'. In this fanfiction, it explores different parallel universes where the Tenth Doctor and Rose's relationship takes on various forms. It's full of creative ideas and really makes you think about the possibilities of their relationship.
Romance is also quite prevalent, although not in a lemon way. It can range from a slow - burn, unspoken attraction to a more overt declaration of love. These romances often explore the unique dynamic between a human reader and the time - traveling alien Doctor, with all the challenges and joys that come with such an unusual relationship.
In these fanfictions, a frequent theme is time - related chaos. Since they are both time - traveling Doctors, they might accidentally disrupt the time - space continuum and have to fix it together. There's also the theme of self - discovery. As they interact, they might learn new things about themselves. For instance, the Tenth Doctor could learn to be more carefree from the Eleventh Doctor, and the Eleventh Doctor could learn about the importance of taking things seriously from the Tenth Doctor. Additionally, the theme of nostalgia can be present. The Tenth Doctor might remember his past adventures, and the Eleventh Doctor could be intrigued by them.