Stranger Things: Winona Ryder and David Harbour improvised their big season four moment

Spoilers follow for the ‘Stranger Things’ season four finale

Winona Ryder and David Harbour improvised a key emotional moment between their characters on Stranger Things.

The hit Netflix sci-fi series concluded season four last week (1 July), with two extended episodes.

Spoilers follow for Stranger Things season four, volume two...

A Twitter account run by the show’s writers confirmed that the actors, who play Joyce Byers and Jim Hopper respectively, only decided on the day of filming that their characters should kiss for a second time this season.

The first kiss, however was scripted. After almost four full seasons of romantic longing – plus a protracted scene of flirting when Joyce rescues Jim from a Russian prison – the characters finally shared their first kiss as a couple.

But the second kiss, which happens just after Jim assures Joyce they will survive the ordeal and make it back to their kids, was agreed upon by the actors.

The emotional scene is one of several big moments from the lastest Stranger Things episodes that have been revealed to be improvised on set. You can read our full review of the “lavish yet intimate” season here.

Actor Joseph Quinn, who plays Hellfire Club leader and reluctant hero Eddie Munson in season four, ad-libbed his encouragement when Robin (Maya Hawke) doubts Steve’s (Joe Keery’s) ability to take command of a hot-wired camper van.

On Twitter, the Stranger Things writers confirmed that Eddie’s reply – “Harrington’s got it... Don’t ya big boy?” – was Quinn’s invention.

Sadie Sink and Caleb McLaughlin in ‘Stranger Things’ (Netflix)

The writers room account also confirmed two other affecting moments from volume two were improvised.

Quinn added the emotional declaration “I love you, man” to the script as Eddie laid in the arms of his friend Dustin (Gaten Matarazzo) during his character’s final moments.

And when Max (Sadie Sink) appears to be dying, a distressed Lucas Sinclair (Caleb McLaughlin) calls out to his scene-stealing little sister: “Erica, help.”

McLaughlin added the stirring cry for help himself.

Stranger Things is available to stream now on Netflix.