Percy is a rather cheeky, but kind engine. He normally behaves well, yet he also gets himself in trouble by jumping into situations without adequately thinking them through first. He is incredibly accident-prone and has many accidents, sometimes due to his own silliness or his tricks backfiring. He loves teasing other engines, especially bigger ones such as Gordon and James, but is always brought down to earth in due course by anyone who gives him the moral to learn. He can also be somewhat timid. Percy can also be questionable and naive to certain difficult words: he will constantly use malapropisms in sentences and mispronounce a word he heard wrong.

They type of voice I'm looking for Percy is a voice that keeps true to him being young, but more grownup young to highlight his maturity overtime as it develops. Something like Eddie Glen's Percy when he was voicing the character during the director's cut.

Example: https://youtu.be/hwchw1ug-mM?si=u_rhqs_zVthTVspZ