"We all have that one, grumpy, heavily armed Uncle from the future," Reynolds shared on Twitter Monday alongside a close-up image of Brolin in costume as Cable.
Brolin is seen notably sporting the characters signature mechanical eye and scared face. The actor is holding up his finger to his mouth in the image.
In a second photo shared by Reynolds, Brolin is featured carrying a large gun and sporting Cable's metal arm along with a teddy bear hanging by his side.
"DeadPool 2: Your premium #Cable provider," Reynolds wrote alongside the additional image.
Brolin was cast as Cable in April. The 49-year-old has since shared on social media the makeup work that goes into making him appear as the X-Men character.
Cable, also known as Nathan Summers, hails from the future and is the adult son of X-Men character Cyclops. He is often paired with Deadpool in the Marvel comics as the duo shared a 50-issue series together.
Directed by David Leitch, Deadpool 2 arrives in theaters June 1, 2018 and also stars Zazie Beetz as mercenary Domino, Leslie Uggams who is reprising her role as Blind Al and Hunt For The Wilderpeople star Julian Denison.