Roman Numeral I (or Romy) is a white lab mouse, the son of Pinky and the Brain thanks to a cloning mistake in which one of Pinky's toe nails contaminated Brain's tissue sample. Like one of his 2 dads, he is voiced by Rob Paulsen.
Romy is a mesh of both Brain and Pinky's personalities. Though he has no desire to take over the world (much to Brain's disappointment), he is very independent and intelligent enough to make it on his own and follow logic thought processes. However, he also exhibits some of Pinky's dumbness. He sends a letter to Pinky telling them not to try and find him and his new girlfriend Bunny , though his address is at the bottom of the page.
Romy has a straight tail, pink eyes, and a severe overbite. He is taller than Brain, but shorter than Pinky.
Season 02, Episode 11 "Brinky "