Can somebody please explain the motives of the killers in the ';Scream'; trilogy?

Why did they want to kill Syd, and they won't be happy until she is actually dead? I skipped too many scenes because some characters annoyed me.Lol.Can somebody please explain the motives of the killers in the ';Scream'; trilogy?
Ok, in the first one, Billy wanted to kill her because he believed her mother was having an affair with his father and was the reason for the split of his parents (and Stu was just helping out).


In the second movie, Billy's mother wanted Syd dead because Syd killed Billy. The other guy was also just an accomplice.


In the third and final movie, the killer was Syd's long lost brother who was upset because their mother basically told him he wasn't wanted.Can somebody please explain the motives of the killers in the ';Scream'; trilogy?
1st movie was because Sydney's mom was having an affair with Billy's dad and she left after she found out.


2nd movie was Billy's mom getting back at Sydney for killing Billy


and 3rd movie was Sydney's half brother who got the shaft while Sydney got everything.
I think they were all united in their hatred of the show ';party of five';. Same thing with 'i know what you did last summer', and I think thats why matthew fox is trapped on the dharma island on 'lost'
Revenge %26amp; Jealousy!! The actual killer was Syd's Bastard brother.
At the end of the third film, we finally know all of the details. It is a half brother of Sydney that feels he got the shaft while she got the love.
Sydneys mom was flash her stuff around like she was Sharon Stone,and she's no Sharon Stone..
Well in the first movie it was because Syd's mom had an affair with the killers (was it billy?) father and caused HIS mom to abandon him or something like that....Stupid stupid stuff...