Dimitri is one of the main characters in 20th Century Fox's animated classic (well, it should be considered a classic anyway), Anastasia. We don't know much about him except for a few things like:
He's a conman.
According to the Anastasia artbook he's around 20-21 years of age.
He has a dry sense of humor. (example: Vlad shivers and states, "She'll freeze in here." Dimitri looks up and says, "she can thaw in Paris")
Underneath the conman facade he is actually a very caring individual---he'd just lost his way for awhile.
He didn't know how to waltz before he and Anya were thrown together by Vlad.
He apparently hates dogs, with Pooka being the eventual exception to the rule.
He apparently hates it when a woman has a mind of her own. *snorts* Rrriiiiggghttt, Dimitri, we believe you. Not.