I saw this in a message about a reorganization.

Problem:
One does not “fulfill” a role.

Explanation:
The verb “fulfill” means to bring into realization.

What the message writer meant to say was that he had asked his team members to perform the duties of new roles (that he described later in the message).

One meaning of the verb “fill” is to perform the duties of.

This leads us to the solution.

Solution:
“I have asked my team members to fill the following roles.”