I just want to discuss the series and the upcoming season 4.
A key thing would be the cure for the brothers. I think Hayley would have to explore the origin of werewolves to find a cure. I always wondered why they had venom in the first place. Vampires are vulnerable to werewolves due to them being involved in their creation, and magic made their venom dealt for balance. I think the original packs were made to eliminate a magical threat, and for some reason this draws them to go after vampires. So the original counter to venom could work.
Marcel bite is so deadly due to multiple venoms and white oak.
Hayley and hope might be immune to the bite, and so their blood could be part of the cure.
I wonder if vervain and wolf bane would help.the vervain to counter the magic of a vampire bite, and wolfsbane to counter the venom magic.

I want to see more about hope potential. She is a whole new werewolf bloodline. I wonder how much of her nature could be shared via that alpha binding ritual. Technically Hayley is an undead, so the ritual might not be have effective. I have this idea that if you check the family of any wolf, you will find a witch ancestor. What if hope can allow her pack to access magic?
Vamps are tied to the sun, wolf are tied to the moon, while witches are tied to the earth. I wonder if a Tribrid might be immune to wolfbane so share that.