Caillou is the main antagonist of the Caillou Gets Grounded and the secondary antagonist of the Dora Gets Grounded series. He is also the most overrated GoAnimate character of all time.
Caillou is a mischievous 17 year old teenager. He wears a yellow T-shirt, blue shorts, and red shoes. Caillou is much taller than Dora, and much taller and older than his original 4-year-old counterpart in the original Caillou, although some people prefer making him his original size. Usually, he is voiced by David or Ivy. Also, He has a strange obsession over Chuck E Cheese's that he is still trying to get over but always fails to resist.
Though Caillou's age depends along people's videos, Caillou is usually between 10 and 16, and he is often in 12th grade. If Caillou was 4 when the real series premiered on September 15, 1997, he might have been born on September 15, 1994 and would've been 22, but most users do not use this. Since Caillou was created in 1989, that must be his real birth year. As of 2017 he would be 28, and that means most of Caillou gets grounded videos possibly happen in the 1990's and 2000's, but those kinds of stuff aren't really that specific.
Caillou is a mischievous child/preteen/teenager who always likes getting into trouble and do horrible things. He can never resist the temptation of misbehaving and always throws tantrums, and due to this he is very infamous. He is very obsessed with Chuck E. Cheese's and he is presumably their Number 1 customer. There are chances that he has a mental disorder, probably severe ADHD, Conduct disorder, bouts of autism or even Reactive Attachment Disorder due to his parents' abuse. The criteria seem to fit a lot. He may have more than one condition.