An article that Arthur finds at work paints Percy as a quiet individual that seldom talks to strangers. When viewing the article, Arthur hears Percy calling out to him frantically, with the sound of a train's wheels, a whistle, and well as a train conductor's voice in the background.
In the Percy's Best Friend encounter, Edmund MacMillan is shown to have been Percival's best friend. During Arthur and Edmund's exchange in the encounter, Ed mentions to Arthur that Percy said he was a good brother. Edmund also mentions that Miss Victoria believed Percy was dim, while Edmund believes he was "Smart, and he never lied
It is confirmed that Percy is “slow” as stated by Percy himself in the flashback, “Lies”. Percy is also known to not care to wear clothes around him and Arthur’s house when they were kids nor wouldn’t bother to care if he walked outside naked. On many occasions Arthur talks about how Percy wouldn’t care to fit in, mainly because he wouldn’t understand. Percy tends to repeat himself when he is confused or doesn’t understand Arthur. Percy will often say, “I can’t hear you.” when he doesn’t understand what Arthur is trying to explain. Though Percy maybe slow it is obvious that he is high functioning and also very good at learning languages as shown by his ability to understand and learn Latin in the flash back “Latin”. Percy also has shown being high functioning when playing against Arthur in the flash back “Chess” when Percy ask Arthur why he’s being stupid. Arthur asks what Percival means and Percy tells Arthur that he’d lose in four turns then proceeded to show Arthur.
Percival is believed to currently be in Germany or Russia.