He generally tries to portray a princely character, but is easily flustered and goes off into an "Emo Corner". The twins Hikaru and Kaoru Hitachiin usually love to tease him until this desired effect.
Tamaki is in love with Haruhi Fujioka, but does not realize it until the very end of the anime (and in the middle of the manga). He calls her his "Little girl" for most of the series.
He is the illegitimate child of his father (who is the headmaster of Ouran Academy) and his mother (who he hasn't seen in years). He also tends to call Kyouya Ootori "Momma".
Though he tends to think that he comes up with the ideas, it is really Kyouya who is behind all of his brilliant schemes (generally. The ones that seem especially ridiculous are typically completely Tamaki-concocted).
By the end of the anime it is arranged that he marry Eclair; little does he know that this was his key to seeing his mother again.
By the end of the show it is revealed that his and Kyouya's father are trying to have their son marry Haruhi.
"H-how could you say that?! D8>"