Because you like Spike in Buffy the Vampire Slayer

Randy Marsh is a geologist and Nobel Prize winner who is into binge drinking, starting riots, the Food Network, and P.F. Changs. See them in South Park.

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

Konata Izumi has a live-now, worry-later view of the world. See them in Lucky Star.

He's the great Black Star, and he's come to assassinate you. See them in Soul Eater.

After Rintarou Okabe develops the Phone Microwave, some of his fantasies start to seem uncomfortably real. See them in Steins;Gate.

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.

England may cultivate the image of a well-bred gentleman, but he has both the temper and mouth of a seasoned sailor. See them in Axis Powers Hetalia.

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.

What Mako Mankanshoku lacks in common sense, she makes up for in sheer optimism and force of personality. See them in Kill la Kill.