Sentence:  Forgetful Hiro can remember everything up to being ten, but nothing since then, including stabbing Sylar at the end of Volume 1. But, of course, "<WSD>Stabby</WSD> Hiro" can remember being ten as well. So Forgetful Hiro can remember Ten-Year-Old Hiro, and so can <WSD>Stabby</WSD> Hiro, but Forgetful Hiro can't remember <WSD>Stabby</WSD> Hiro. 
Meaning of the word marked with <WSD> tags:  acting in a violent and/or deranged manner