Point of clarification: only male half-breed vampires are venomous, we find this out at the end of Breaking Dawn
when Alice arrives. The females are not venomous.
readmymind wrote:I haven't read it in a while, so I might be wrong, but I think I remember something about how werewolves and full vampires can't do anything romantic, because it could kill one of them.
My understanding in why full vampires and werewolves (or at least shape-shifters since we are referring to Jacob and at the end of Breaking Dawn
it is confirmed that they are not "children of the moon" but more aptly named shape-shifters) is that they smell so horribly to each other, they would not want to be intimate with someone who repulsed them so much. Plus the history that Jacob's pack has with vampires also would prejudice them against vampires (full vampires) as well. Look at how tenuous the treaty is between them, the relations between them, even when Carlisle is trying to help Jacob.
When Jacob first lays eyes on Renesemee, he imprints, we never hear once she was born, that she smelled bad to him. Therefore that might explain part of the attraction, plus, I agree, Renesmee is half-human, her heart beats, she grows which leads me to believe that her reproductive system should work as well. Therefore she should be able to carry children if she chooses once she is older. Considering that Jacob is an Alpha wolf he would (well the werewolf in him) would look to find a strong mate able to breed more alpha or at least strong werewolves. Renesemee is an excellent choice, she is half-vampire so she is human but with some of the advantages of a vampire, making her a perfect mate to a werewolf alpha.