8 things you need to know as Versailles returns for series two

1. King Louis goes off the rails

When we last saw Louis, his brother Philippe had left the palace and said he didn't want anything to do with him, and the love of his young adult life, Henriette, had died. Meanwhile he had built this monumental palace where he could trust nobody.

In the opening sequence of season two the insomniac King is sleepwalking in the gardens and awakens in fear in the lake he has built. Is he losing his grip on reality?

Blagden reveals: "We start season two seeing a man who's very isolated and who stops listening to the people that he should be listening to and starts taking advice from the wrong people, and it's a perfect example of what happens when you have all of that power – how do you keep it? We see him starting to become more and more out of control through the first part of this second season."

2. The 'affair of the poisons' makes Louis ultra-paranoid

Now we are entering a darker period of Versailles' history known as the "affair of the poisons", a murder scandal which began in 1677 and lasted until 1682.

Blagden explains: "Louis has created this monster that he couldn't quite control, in that the more people he invited and the more nobles he tried to cram into this building, the more they started to misbehave.

"Love potions became a very fashionable thing at the time, sort of like the equivalent of modern day drugs in a way. Powders and potions that you'd use to enhance your experience of life.

"They became very popular at Versailles - so much so that people started to abuse them and people would often lace them with poisons; it was a very easy way to get rid of people that you didn't want or you didn't like, or someone who was climbing the social ladder too quickly above you.

"So we start to see the underbelly of this monster that Louis has created, and all of the characters go on this twisting journey downwards into darkness, Louis particularly, and he has to face a lot of his own demons through the course of season two."

3. Philippe ups the ante with his crossdressing

"The crossdressing does appear again but it comes in the most unexpected way, let's just say that," teases Vlahos, who also has his eye on his "dream job" as Doctor Who.

We saw Philippe dressing up as a woman in season one, but that was only a brief appearance. This time Vlahos had to wear a "painful" corset and dress for two whole weeks.

There will also be plenty of nudity - even from the men, after Vlahos complained that it wasn't fair that the women were expected to get naked and the men got to keep their clothes on.

4. Montespan tightens her control

"The start of season two really is all about Montespan," says Blagden, referring to Louis' mistress Madame de Montespan, played by Anna Brewster.

"It is very much her story, in a way, that we're following. And two years have passed since the end of season one to the beginning of season two, and we've really now seen how she has established herself as the most powerful woman in France or in the world at that time.

"We start to see how that influence that she's gained and that favour that she's gained with the King really starts to affect him and his mind, and all of the day to day decisions that he has to make are filtered through the Montespan filter, and we even see him taking her advice on some rather monumental decisions and ignoring his most trusted valet, Bontemps."

5. King Louis goes to war

As Louis feels more and more out of control, he decides to go to war. This is, as Blagden says, is "something that he's not designed to do." Unlike his brother Philippe, who was famous as a warrior, he never excelled as a military leader.

6. Philippe gets married again

Reflecting historical reality, Philippe marries again after the death of his first wife, even though he has no choice in the matter and certainly has little interest in women. His new wife is Princess Palatine, played by newcomer Jessica Clark.

"Do you know what, I think it is actually a happy marriage," says Vlahos. "I mean, apart from the fact that he's been forced to marry her for political reasons, on Louis' behalf, they actually grow to like each other and have a very fond affection towards each other."

7. The Chevalier returns

Despite having been exiled to Italy, Philippe's old love interest Chevalier (Evan Williams) also comes back on the scene when the King realises he really needs his brother at court.

Blagden says: "Louis very quickly realises in this second season that as much as he doesn't agree with his brother's methods, what he brings to the building and this community that Louis' trying to create in Versailles is extremely important element, the sparky fiery personality that Philippe brings, it's an important element to have in the building, whether it's entirely useful all the time or not. And in realising this, it means that he has to get him back."

"Louis is the person that has exiled him and is using Chevalier as a tool, as a currency to woo Philippe back into Versailles," Vlahos explains. But what happens now Philippe has a wife? "It's almost like a very unwanted menage a trois, let's just say that."

8. The royal brothers don't butt heads so much

Blagden and Vlahos didn't actually spend much time together filming series two, because Louis and Philippe were given different storylines.

Vlahos says: "In season one we really hammered home that relationship between the two brothers, and it was almost like the heartbeat, the skeleton of the show. In season two, they're keeping us apart, and when they do eventually meet there are fireworks, but it's almost like they're having a different argument now. They're a bit older, they're a bit wiser, their relationship has evolved now into I guess much more of a royal relationship rather than a sibling relationship."

And when Louis is at his low point and completely shutting everyone out, "Philippe is the only person in court that Louis really does listen to."