A really interesting 'Doctor X Tardis' fanfic I've come across is 'Tardis Tales'. In this fanfic, the Tardis has a sort of consciousness that the Doctor tries to fully understand. It delves into the mystery of the Tardis' inner workings and how it has a connection to the Doctor on a deeper level than just being a ship. It's a short but engaging read that will make you look at the Doctor - Tardis relationship in a new light.
Often, it involves exploring the unique bond and adventures between the human Tardis and the Doctor. There's a focus on how this unconventional setup changes their dynamic and the challenges they face together.
Good character development in both the Doctor and the Tardis is key. If a fanfic delves into the Doctor's past experiences with the Tardis and how it has shaped him, and at the same time shows the Tardis evolving in some way, it's bound to be great. For instance, the Tardis could develop new functions based on the Doctor's needs over time. Also, a vivid description of the Tardis' interior and how it feels to be inside it can really make a fanfic stand out.
Well, in the 'harry built the tardis fanfic', first of all, it's a really cool concept. Harry is known for his adventures in the wizarding world, and the TARDIS is such an iconic part of Doctor Who. The fanfic might start with Harry stumbling upon some ancient plans or technology that gives him the idea to build the TARDIS. He could face many challenges, like getting the right materials. And once he starts building, he might have to deal with the magical and scientific aspects that don't quite match up in the normal sense. It could be a story full of discovery, adventure, and the combination of two very different fictional universes.
A female doctor I heard of was very good at dealing with children patients. She had a warm smile and a gentle touch that made the kids feel at ease. Her ability to communicate effectively with the young patients and their parents was remarkable. This made her a very 'sexy' doctor in the sense that she was great at her job and had a wonderful bedside manner.
I haven't actually read this fanfic. But generally, it might be about Harry from the Harry Potter universe building a TARDIS which is from Doctor Who. It could involve him using his magic skills to construct this time - and - space - traveling device. Maybe he combines spells from Hogwarts with the technology (in a magical way) of the TARDIS.