Taggart is the head scribe at Hidden Valley bunker, but most believe he is incompetent and always taking the credit of others. He focuses mostly on VR simulations for the soldiers so they will be combat ready.
Conversations with other Brotherhood of Steel faction members in the Hidden Valley bunker suggest that Taggart is a lecher who promoted Watkins out of her classes not so much for her intelligence as her appearance.
When Veronica Santangelo is in your party she'll greet him with, "Scribe Taggart! It's your favorite student!"
Various members of the Brotherhood say that the Elder has him working on a secret project.
Taggart's name and personality is reminiscent of "James Taggart" of Atlas Shrugged.