Definitely not true. Rikki Tikki Tavi is a work of fiction. It was crafted to bring adventure and imagination to the readers, not based on real events or people.
Well, Tikki and Plagg are kwamis in the Miraculous Ladybug universe. Their love story is rather unique. They have a very old relationship. They bicker a lot like an old married couple. But beneath all that, there's a deep connection. They are two sides of the same coin in a way, with Tikki representing creation and Plagg representing destruction. Their love is shown through their understanding of each other despite their differences. They have been together for a very long time and have a bond that is hard to break.
One possible fanfiction could be about Marinette's daily life with Tikki. For example, Marinette could be having a tough day at school, getting bullied by Chloe. Tikki, being her kwami, tries to cheer her up by suggesting they make some special macarons. They then spend the evening in Marinette's room, sharing stories and laughing, which helps Marinette forget about her bad day.
In 'Rikki Tikki Tavi', Rikki Tikki has to face and defeat two snakes to keep the human family safe. There's a lot of tension and excitement as he shows his courage and skills.
The main conflict in 'Rikki Tikki Tavi' is between the mongoose Rikki Tikki and the snakes Nag and Nagaina, who threaten the safety of the human family and Rikki's new home.