[Krono]

Originally Posted by Kaijo

Well, technically speaking, he doesn't have any clue where to look. And most of the "missions" have been things that needed to be done. He couldn't just ignore them. I get the feeling that he hopes to pick up clues while doing missions, to at least give him a place to look.

Spoiler for manga spoiler:

You'll remember that when Gildartz mentioned the Black Dragon, Natsu immediately wanted to go and seek it out, in the hopes it would know about Igneel. But Gild held him back and said the dragon would be gone, persuading him not to go because it would do no good.

This pretty much, though there's a number of boring routine missions offscreen that the characters take to earn a living.

In addition to having no leads to follow, people don't seem to realize that Natsu places his friends and life at Fairy Tail as pretty much equal(if not greater) in importance to Igneel.

In other words, while he wants to find his father, he's not going to let that desire consume his life.