The Eternals in Marvel Comics are a race created by the Celestials. They have unique abilities and a complex history. Some notable Eternals include Ikaris, Sersi, and Thena.
It's hard to give a definite answer. The status of the Eternals in Marvel Comics changes frequently based on different story arcs and creative directions. Sometimes they might be in the spotlight, while in others they might take a backseat.
In Marvel Comics, it's a bit hard to give an exact count of the Eternals as new characters are sometimes introduced or existing ones are reimagined. But you can expect a diverse and substantial group.
The number of Eternals in Marvel Comics is fluid. It changes over time and across different comic runs. Some notable Eternals include Sersi, Ikaris, and Thena, but there are many more who have appeared throughout the comics' history.
You could write a fanfiction where some of the Eternals get separated from the group and have to survive on their own in a hostile part of the world. They would have to use their powers in new and creative ways to stay alive and find their way back to the others. This would show their individual strengths and weaknesses more clearly.
First, research the characters. Know their powers, personalities, and backstories. For example, Ikaris is very powerful and loyal, but also has his own internal struggles. Then, come up with a simple idea, like a day in the life of an Eternal on Earth. Just start writing and don't worry too much about grammar at first.