Joaquin Phoenix looked lovingly at his sister Rain as she supported him on the red carpet at the Joker: Folie à Deux premiere on Wednesday. 

Attending the event, which took place during the 81st Venice International Film Festival, the siblings stood side-by-side while smiling for photos at Sala Grande. 

Folie à Deux will see Joaquin, 49, reprise his role as Arthur Fleck AKA Joker and is set for release on October 4.

The actor wore a smart black tuxedo with a white shirt, bow tie and a pair of sunglasses for the hotly-anticipated event.  

Rain, 51, wore a brown velvet gown and donned stylish oversized shades as she posed with her brother.

The film is the much-anticipated follow-up to 2019's Academy Award-winning Joker, which earned more than $1 billion at the global box office and remains the highest-grossing R-rated film of all time.

The second instalment finds Arthur Fleck institutionalised at Arkham awaiting trial for his crimes as Joker.

'While struggling with his dual identity, Arthur not only stumbles upon true love, but also finds the music that's always been inside him,' a press release shared.

The last time that Joaquin played The Joker, Arthur Fleck, he had to drop three and a half stone. He went on a diet of lettuce, asparagus and apples. 

Five years later he has returned to the Oscar-winning role again in – and says that he had to lose almost the same amount of weight once more, and is never doing it again.

Speaking at the Venice Film Festival he said: 'I'm not going to talk through specifics of the diet, because I just think nobody wants to hear that.

'But this time, it felt a bit more complicated just because there was so much dance rehearsal that we were doing, which I didn't have last time. 

'It felt a bit more difficult, but it is safe. But you're right, I'm now 49, I probably shouldn't do this again. This is probably it for me.' 

He added: 'I know I was responsible last time for talking about it, but it's difficult to do so. 

'That becomes your obsession because you're working the entire time to get to a certain weight.

'So then you end up talking about it, and then it just sounds like an actor going on and on about how much weight they lost.

'By the end of that run I was so sick of myself and angry at myself for making such a big deal about that part, because you just do what you're ****ing supposed to do. So this time I was like, 'I'm not going to do that'.'