All info was provided at http://mryoung.wikia.com/wiki/Derby
Derby is Adam's best friend and also his student, a line that Derby’s more than happy to blur. A self-proclaimed Don Juan, in truth, Derby is a class clown and a bozo with the ladies. Dabbling in everything from tango to one-man-bandmanship, he’s a lover of the arts, especially the fine art of pranking. He appears in the live action series, Mr. Young.
Derby is often upbeat and fun, but he can be dumb and wacky. He is a class clown, who loves to pull pranks and joke around. He doesn't like school, and said the only reason he came to high school was for the cheerleaders. He is unsuccessful with the ladies, even though he thinks he is a ladies man. He has a good relationship with Adam, is a 'frenemy' with Slab, and has a crush on Ivy.
Derby often doesn't really pay attention to Adam, and falls asleep in class when Adam is sleeping. Derby sometimes tries to get Adam to leave the school, and sometimes assists Slab while doing it. But, nevertheless, he still counts on Adam to help him, saying that he knows he is irresponsible, but expects more from Adam . Derby sometimes goes along with Adam's plans, though, like when Adam suggested they join the ballet class, it turned out being to Derby's advantage.
Slab and Derby have a 'fox in a henhouse' kind of relationship. Derby is known for being Slab's main bullying target, Slab puts him in a trash can every single day. In the episode "Mr. Honest", it is revealed Derby thinks Slab is a big, dumb idiot, but that he thinks of him as a friend, and Slab feels the same way.
Derby has been known to have a massive crush on Ivy. Adam is sometimes offended and grossed out that Derby has a crush on his sister, but Derby doesn't care. He has tried do many things to seduce her; in "Mr. Roboto", he auditioned to be Ivy's fake boyfriend. In "Mr. Talent Show", he did a magic trick with Ivy and described her as his 'beautiful assistant'. And in "Mr. Honest", Derby tried to get Ivy to take off all her clothes. Ivy is grossed out by him, but that's not gonna stop him.
- He did ballet and was the main role, the Prince in Swan Lake.
- He is not very bright.
- He carries around a prank kit, as he loves pranks.
- His nana lost a foot in a vacuum cleaner accident, and keeps it in a box under the sink.
- He has a pet hamster named Tickleschmootz.