A common problem in multi-cat households. Some cats simply cannot get along, even though the websites claim bengals love other cats. You have a very serious problem on your hands because the aggression is now directed towards you as well.
First, I'd take the cat to the vet to see if there is a hormonal imbalance somewhere. I'd want to make sure there is nothing medically wrong causing this behavior. Since the aggression seems to be towards Thor, you need to try to keep them separated. There are a couple of things you might try:
Make sure every single cat has their own territory in your home. Since you have five cats, that means at three to five cat trees. Bengals love to climb and be up high in the room. In order to live in harmony, the cats need to know they have their own space. Catification is a great thing where you create a super highway for the cats that can include shelves on the walls, bookcases -- something where Thor cannot get trapped and has an escape route. Many times when you give each of the cats a large enough space, they don't worry about the other cats.
You might try looking at
http://spiritessences.com and check out their formulas to help with bullying. I don't use anything from there, a couple of gals are trying it on their cats here, and we've had another poster who thinks the whole holistic thing is rubbish -- and that's his right. You are trying to find a solution to a huge problem, so investigate everything.
I would suggest feeding your bengal and Thor where they can see each other but cannot have contact. They should concentrate on the food while knowing the other one is there, but there is no aggression and Thor can associate good things with your bengal.
You need to be playing with your bengal and wearing the girl out. Bengals are high energy cats and playing with them to the point they are worn out can help against their aggression. Make sure you play with Thor as well. All your kitties should be getting lots of play time.
Freya sounds like a typical bengal to me, she's just going overboard with the aggression. Diverting her attention from Thor with food and toys should help. Making sure Thor has an escape route to get away from Freya will help. His confidence level is waning and it needs to be built up. He is still growing and at some point will be a much larger cat to compete.
Naturally, there are medications that can be given, but side effects can be bad and not all cats metabolize mediations the same way. But, I'd start off with a visit to the vet to make sure everything is okay with Freya. Then catify your home. Jackson Galaxy has a great book out called "Catification" that features ideas from other cat owners -- there are some terrific stories in there and yours may be one of them.
All I can say, is keep trying different things until you hit on something that works for your kitties. Good luck and keep us posted!