Natsu is called Salamander because he is a Fire Dragon Slayer, and Salamander is a type of mythical creature associated with fire. In the world of Fairy Tail, Dragon Slayers are named after the type of dragon they have been taught by, and Natsu was taught by the Fire Dragon Igneel. Therefore, he is known as the Salamander because of his fiery abilities and connection to fire dragons. **

Natsu becomes End through a series of events in the Fairy Tail series. He is originally a human who was raised by the dragon Igneel and later discovers that he is actually a demon created by Zeref, known as Etherious Natsu Dragneel (End). Natsu's transformation into End is triggered by the use of powerful magic and the influence of Zeref's dark energy. This transformation gives Natsu enhanced demonic powers and a darker, more destructive personality. **

Natsu meets Igneel, his foster father and a powerful fire dragon, when he is a young boy. Igneel saves Natsu from a group of bandits and takes him under his wing, raising him as his own son. This encounter marks the beginning of Natsu's journey as a Dragon Slayer and sets him on the path to becoming a powerful wizard. **

Natsu and Lucy are two main characters from the popular anime and manga series, Fairy Tail. They are members of the Fairy Tail guild and share a close bond throughout the series. Natsu is a fiery and passionate Dragon Slayer, while Lucy is a celestial wizard with a kind and determined personality. Their relationship is a central focus of the series, and fans often speculate about the nature of their feelings for each other. While their relationship is not explicitly romantic, their deep friendship and mutual support are a significant aspect of the story. **

No, Natsu does not appear in Edens Zero. Edens Zero is a separate manga series created by Hiro Mashima, who is also the creator of Fairy Tail, where Natsu is a main character. In Edens Zero, the story follows a different set of characters in a different universe, so Natsu does not make an appearance in this series. **

Yes, Natsu eventually gets together with Lucy Heartfilia in the anime series Fairy Tail. Their relationship develops throughout the series, with moments of friendship, trust, and mutual admiration leading to romantic feelings. Fans of the series have enjoyed seeing their bond grow stronger over time. **

Natsu cannot use Dragon Force at will because it is a power that is typically triggered by extreme emotions or situations. It is a rare and powerful transformation that requires a strong emotional catalyst, such as anger, desperation, or the need to protect someone. Natsu has only been shown to enter Dragon Force a few times in the series, and it is not something he can access whenever he wants. **

It is difficult to determine who would win in a fight between Natsu and Asta as they come from different anime series with different power systems. Natsu is a Dragon Slayer with the ability to manipulate fire, while Asta wields an anti-magic sword and possesses immense physical strength. Both characters have their own unique strengths and weaknesses, making it hard to predict the outcome of a battle between them. Ultimately, the winner would depend on the circumstances of the fight and how the characters utilize their abilities. **