Because you like Natasha Romanoff / Black Widow in Marvel Cinematic Universe
Eren Jaeger will erase the Titans from this world until not a single one remains. See them in Attack on Titan.
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.
Basil Hallward is dominated, soul, brain, and power by Dorian. See them in Dorian Gray.
While Cassie Ainsworth's head is always in the clouds, her heart is always in the right place. See them in Skins.
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!!.
The cutest kitty this side of the galaxy, Nepeta Leijon is mischievous, caring, and obsessed with romance. See them in Homestuck.
Sid Jenkins is the ultimate underachiever, but he doesn't mind. Well, he pretends he doesn't. See them in Skins.
Living with a curse, Kyo Sohma is sick of being treated like garbage his whole life. See them in Fruits Basket.
Nadja was feminasty before it was cool. See them in What We Do In The Shadows.
Mr. Pink doesn't tip. Enough said. See them in Reservoir Dogs.
After Rintarou Okabe develops the Phone Microwave, some of his fantasies start to seem uncomfortably real. See them in Steins;Gate.
Misato Katsuragi is never without a beer in her hand or her pet penguin by her side. See them in Neon Genesis Evangelion.