Tough questions....
... but a true wuxia hero would be someone who would have better control over his emotions that the ordinary guy in the street. Therefore, despite feeling angry, hurt, indignant, etc, he *might*:
1. ... first find out from his mother why she killed his father.
2. ... first find out from his father why he killed his mother.
3. ... first find out what the King/Emperor had been doing before he was killed. Was he oppressing the common people, or being lax/negligent in his administration and thus causing the common people to suffer gross injustice?
4. ... first find out from his parents why they killed his grandparents.
5. ... first scream/shout/tantrum; then make a calm and serious attempt to find out why the King/Emperor killed his parents. Then, seek redress if the killing was unjustified. Loyalty to the King/Emperor [zhong1 忠] is dependant on the character of the King/Emperor himself.
6. ... first find out from his parents why they killed his sibling.
7. ... first scream/shout/tantrum; then calm down and find out from his parents why they killed the love of his life because of his filial piety [xiao4 孝] towards his parents.
8. ... first scream/shout/tantrum; then calm down and find out from his best friend why he killed his parents because of his sense of loyalty [yi4 义] towards his best friend.
9. ... first scream/shout/tantrum; then calm down and find out from his best friend/lover and/or the friend/lover's father why that father killed his parents because his sense of fair-play necessitates that he give them a chance to explain themselves.
10. ... first scream/shout/tantrum for an extended period of time; then calm down and find out from the love of his life why she killed his father because his sense of fair-play necessitates that he give her a chance to explain herself. Finally, break up because of his filial piety towards his parents.
A true wuxia hero will do his utmost best to avoid killing another in revenge, because he would have understood the oft-quoted saying: 冤怨相报何时了? "When will the cycles of revenge end?"
My 2 cents...
HYS