When your favorite character die: You wanna punch the TV or PC flat out. "Why the hell did you die? Are you curse to die all along? Do you want me to go crazy!!!!"
When your favorite character didn't match out with your dream leading partner: Bouncing on the seat. "Why? You're not destined to be together!! Are you blind or stupid!! Grahhhh!!!"
When your favorite character suddenly disappear... like forever even after the anime or manga ended: Poker face. "Was he/she even cared for in this manga/anime?"
When your favorite character become psychologically defected: Cover the eyes. "I don't even remember how I like you in the first place, but I don't care!!!! He's/She's so cool. Wahhhhh!!"
When your favorite character turns out to be a killer maniac: Throw the pillow. "If she/he's a killer, he/she should just kill the antagonist of his/her life in the first place. Tsk."
When your favorite character suddenly turns into cross dresser and gender bender: Cry. "You bastard/witch, I even imagine you having babies. huhuhu."
When your favorite character suddenly turns into a pathetic character: Shock face. "Should I still continue? I wanna be the one to kill him/her... if this continue... *sigh*"
When your favorite character turns out to be the antagonist: Not able to move. "Are you serious? Why!!! No!! Not him!! Not her!!
When your favorite character was kissed unexpectedly by your ideal leading partner after all the wait: Clench fist. "Kyahhhhh!!! How could that be so romantic? I have no idea."
When your favorite character have his/her happy ending just like how you wanted: Jumping like crazy, punching the air with a creepy laugh. "Ohh yeahh... oh yeahhh... I knew it... I do... I'm so good. aha... aha... who's the great? It't me, I knew it...
ahahahahahahaha."
That's exactly how I react.