In the functional leadership model, one conceives of leadership not as a person but rather as a set of behaviors that help a group perform their task or reach their goal. Leadership behaviors can be divided roughly into three types:
Substantive, or behaviors directly relevant to performing the group's task, such as proposing possible solutions or providing important information;
Procedural, or behaviors that help direct the group's discussion, such as developing group procedure or testing the degree of agreement among members; and
Maintenance, or behaviors that improve the relationships among the members, such as encouraging silent members or facilitating open discussion.
Any member can perform these behaviors, and so any member can participate in leadership. It was once thought that members always specialized in one type or another, but while that can happen it is not necessarily the case.
If we define leadership simply as "influencing others to some purpose" and we define followership as "becoming influenced by others to accept some purpose", then leadership and followership emerge as two sides of the same coin.
The leadership (foremost individuals) of a mythical swarm of lemmings or the bellwether function in a mob of sheep do not attract many deliberate human emulators.
But the metaphor of a front-runner leadership can occur with or without implied approval: a politician may "lead in the polls" without any "leadership" skills; market leadership of a monopolist does not imply any necessary charisma, and the leader in a running race has followers who may not willingly choose to function as followers.