Dmitri doesn't realize he's being cute - even when he's sulking! He gets so much attention it's little worrying sometimes!
Character-wise, Dmi's really as different as night & day compared to Ian. While Ian is a bit reserved, Dmi is rather "showy". Ian a little timid, Dmi a force to be reckoned with. Well, those traits just make them very, very special to mummy & daddy!
Oh, the most obvious: Ian - being the first born - could do without the little brother and rather enjoys time off sans Dmi... but Dmi, on the other hand, just adores his big "bruver"!