The CEOs of two banks at the center of the outrage over Uncle Sam’s lifeline to Wall Street showed very different sides of their personalities during yesterday’s seven-hour grilling by the House Financial Services Committee.

Vikram Pandit, the cerebral and generally aloof CEO of Citigroup, was unusually lively during his inquisition, frequently raising his hand as he eagerly tried to answer questions.

At one point, during an exchange with Rep. Maxine Waters (D-Calif.) over mortgage mitigation practices, Pandit jumped in to tout Citi’s program.

Bank of America boss Ken Lewis, meanwhile, looked stiff and pale, showing flashes of anger and sarcasm as he was drilled by congressional members. That stood in contrast to the Lewis the public often saw in the past, particularly when he called himself a patriot for rescuing Merrill Lynch and Countrywide Financial.