Maybe it's a legendary Pokemon in disguise. In some fanfictions, legendary Pokemon often play important roles. It could give Ash the egg as a test or because it senses that Ash has a pure heart. Another possibility is that it could be a young trainer who can't take care of the egg anymore and trusts Ash to do a good job.
In this fanfiction, Ash might take really good care of the Pokemon egg. He would probably keep it warm and safe, waiting eagerly for it to hatch. Maybe he'd even talk to the egg, like he does with his other Pokemon friends.
It could be an Eevee. Eevee is a very common yet special Pokemon. It has the potential to evolve into many different forms, so it would be an interesting addition to Fem Ash's team.
His friends like Pikachu for sure. Pikachu would be there by Ash's side, probably as curious as Ash about the Dratini egg. Brock might also be involved. He could use his knowledge of Pokémon to give Ash some tips on taking care of the egg.
Team Rocket would be the most obvious ones. They're always after rare and powerful Pokémon or Pokémon - related items, so the legendary egg would be a huge target for them.
Well, in the fanfiction, Ash might start by being super excited about getting the Dratini egg. He could be very protective of it, constantly checking on it and making sure it's in a safe place. Maybe he'd research all about how to take care of a Dratini egg, like the ideal temperature and humidity.
In this fanfiction, Ash could face a lot of challenges while taking care of the Pokémon egg. There might be other trainers or Pokémon who try to steal the egg. He would have to protect it at all costs. Also, he could meet some new friends who help him with the egg. They might give him advice on how to keep the egg warm and safe. And when the Pokémon finally hatches, it could form a really strong bond with Ash right from the start.
Misty is a very likely candidate. She has been with Ash from the early days of his journey. They have a deep bond and have shared many adventures together. Their relationship has always had a bit of a romantic undertone, so in a fanfiction, it would make perfect sense for them to get married.
I'm not aware of any non - inappropriate 'Ash gets a Pokemon pregnant' fanfiction. This concept is not in line with the family - friendly nature of the Pokemon franchise. Fanfictions usually revolve around themes like battles, training, and the bonds between trainers and Pokemon. A concept like this is quite abnormal and would not be easily found in the realm of proper fan - created works.