A story could also be about the baby's discovery of its unique abilities. It might be able to do something that neither Toothless nor Light Fury can. For example, it could communicate with a different species of animals in the forest. This causes a stir among the dragon community and also makes Toothless and Light Fury very proud.
For Toothless, show his protective side as a father. He could be very cautious about any potential threats to the baby. His past experiences as a Night Fury could make him an excellent teacher for the baby, teaching it how to hunt or hide from danger.
Maybe the baby dragons get lost outside the Hidden World. They encounter different challenges like facing hunters and strange new landscapes. Toothless and Light Fury are desperate to find them. Along the way, the babies make new friends among the local animals who help them survive. The fanfiction could detail their adventures and how they finally reunite with their parents.
One idea could be that a female Night Fury from a far - off land arrives and Toothless has to teach her about the new world he's living in with Hiccup and the Vikings. Their relationship could grow as they explore together.
One great Toothless x Light Fury fanfiction could be 'The Bond Beyond Wings'. It beautifully explores their relationship as they start a family and face new challenges in the Hidden World. Another one might be 'Flight of Two Hearts' which focuses on their courtship in a more detailed and romantic way.
Some interesting Toothless x Light Fury fanfics include 'The Meeting of the Furies'. This one details the first time they meet and the instant connection they feel. 'Toothless' New Mate' is another one. It explores how Toothless adapts to having a new partner in his life, the Light Fury. 'The Light Fury's Influence on Toothless' is a fanfic that looks at how the Light Fury changes Toothless for the better in different aspects of his life.
One plot idea could be Fem Hiccup discovers a new ability in Toothless that no one else knew about. For example, Toothless can communicate with a long - lost species of dragons. Another could be Fem Hiccup gets lost in a strange land and Toothless has to use his instincts to guide her back home. And also, a plot where Fem Hiccup and Toothless encounter a powerful enemy dragon and they have to work together to defeat it using their unique bond.
Another plot idea is that a strange illness starts affecting the dragons in Berk. Toothless is one of the first to show symptoms. Hiccup, being the dragon expert, sets out to find a cure. He and Toothless travel far and wide, facing many challenges along the way. They meet other dragon riders from different lands who may or may not be helpful in their quest for the cure. This journey tests their bond and shows how much they rely on each other.
One plot idea could be them going on an adventure together to discover a new, hidden land filled with strange and magical creatures. They have to rely on each other's unique abilities to survive and explore.
A great plot could be a 'what if' scenario. What if the main character made a different choice at a crucial moment? Like if Feyre didn't go with Rhysand at a certain point. This could lead to a completely different set of events and relationships in the fanfiction.
I'm not sure specifically about 'lemon' fanfictions as they often contain inappropriate content. However, for regular Toothless and Light Fury fanfictions, you can try searching on fanfiction.net. There are many heartwarming stories about their relationship, adventures, and how they interact with the other dragons in the How to Train Your Dragon universe.