Because you like The Spirit of the Puzzle in Yu-Gi-Oh!
Oscar Jarjayes is a sword-swinging, fearless Commander of the Royal Guard who cross-dresses as a man. See them in Rose of Versailles.
Years of being the less desirable Vargas sibling have given Romano quite an inferiority complex, as well as the temper to match. See them in Axis Powers Hetalia.
For the sake of science, Kurisu Makise will persevere no matter how deep into the dark secrets of the world she finds herself. See them in Steins;Gate.
While his twin tries to save lives, Millions Knives does the best to end them. See them in Trigun.
Prideful and psychotic tendencies combine to make Dr. Eggman a dangerous and villain who will squash anyone in his path. See them in Sonic the Hedgehog.
Gou Matsuoka offers to help as manager of a swim team, believing that they're the only ones who can help her brother. See them in Free! Iwatobi Swim Club.
Konata Izumi has a live-now, worry-later view of the world. See them in Lucky Star.
Applejack's practicality complements her caring nature. She is the loyalest of friends and the most dependable of ponies. See them in My Little Pony.
Beneath Yuji Sakai's meek exterior lies an exceptionally keen mind and a strong inner will. See them in Shakugan no Shana.
The vampire that killed Zero Kiryu's family also infected him, and he starts to crave blood, much to his horror. See them in Vampire Knight.
Shana is a red-haired warrior with a black-and-white worldview. See them in Shakugan no Shana.
Everyone is just a chess piece, and Izaya Orihara is a master player. See them in Durarara!!.