How does natural law play into virtue ethics?

[Daniel]

St. Thomas speaks of the natural law, but St. Thomas is a virtue ethicist.

I am wondering how these two ethical theories fit together? They seem quite different. Virtue ethics is character-based (the virtuous man's adherence to the natural law follows from his virtue), whereas natural law theory (if I understand it correctly) is action-based (and is seemingly closer to Kant's theory).