What Is the Connection Between Bartholomew and Nathaniel?

There's nowhere in the New Testament where Bartholomew is given a speaking part, at least under that name. While Matthew, Mark, and Luke talk about Bartholomew, the gospel of John mentions someone named Nathaniel. And he's actually mentioned in two passages in John, after the resurrection,. But really only he's just listed as one of the disciples who are out fishing when they're going to see Jesus on the seashore.