Because you like Kathryn Merteuil in Cruel Intentions

With most of the people that Sango loved now gone, the only thing she wants is to kill the demon who destroyed her village. See them in Inuyasha.

After several hundred years of shutting himself out from the rest of the world, Japan's not used to dealing with nations, See them in Axis Powers Hetalia.

He may forget his homework, lose his toad, and fall off brooms, but Neville Longbottom can also single-handedly destroy villains. See them in Harry Potter Series.

Given his ability to wrench street signs from the ground, Shizuo Heiwajima is a useful one to have in dangerous Ikekuburo. See them in Durarara!!.

Kyoya Ootori is possibly the only person who could reasonably go from VP of a school club to ruling the world. See them in Ouran High School Host Club.

Years of brutal winters, foreign invasions, and crippling loneliness have left Russia's mental state far from wholly intact. See them in Axis Powers Hetalia.

A nurturing, selfless, and level-headed leader, Makoto Tachibana loves looking out for his friends. See them in Free! Iwatobi Swim Club.

From his attire to his form while running, aesthetics rule Rei Ryugazaki's life. See them in Free! Iwatobi Swim Club.

Insightful about everyone else's neuroses, Rose Lalonde is not as aware of her own. See them in Homestuck.

Yuri Plisetsky's a hotheaded punk off the ice, incredible artist on it. See them in Yuri on Ice.

Living with a curse, Kyo Sohma is sick of being treated like garbage his whole life. See them in Fruits Basket.

Jade Jade Harley might not be the best at reading social cues, but her bravery and selflessness means she's a great friend to have. See them in Homestuck.