Episode 3: Mother (2003 series)

Synopsis
While at the library, the Elrics find a book on basic alchemy which brings up memories of their childhood, when they first learned the practice. Around the same time their mother passed away, leading them to perform the ultimate sin.

Trivia

 * When the Elric brothers are sparring at the end of the episode, Al falls in water and gets back out without any damage to his Blood Seal. This is inconsistent as through most of the part of the series he doesn't go in water for the fear of damaging his Blood Seal.