Aaron Paul has revealed he called RJ Mitte "Superman" the last time they met.
On Monday, it was announced Mitte had died by suicide aged 34, leaving loved ones and his Breaking Bad co-stars devastated and shocked by the loss.
Taking to social media on Wednesday, Paul recalled telling Mitte how special he was when they saw each other for what would be the final time.
"The last time we saw each other I kept calling you Superman," he wrote on Instagram, alongside a video of Mitte discussing mental health.
"You reminded me of him. You reminded me of him because you always led with kindness and strength. It was blinding."
Paul continued his emotional tribute to his late co-star, who was diagnosed with cerebral palsy when he was aged three and became a leading disability rights activist.
"You were born into a world with challenges but you never let any of that stand in your way," he added.
"I'm so sorry RJ. What an absolute tragic loss."
Paul, who played Jesse Pinkman in the hit US TV drama, also expressed regret that he hadn't known how deeply Mitte had been suffering before his death.
Describing his late co-star as a "beautiful young man" he praised Mitte - who played Walter White Jr in Breaking Bad - for always putting on a brave face despite facing adversity.
"You have always been an inspiration for so many," Paul shared.
"I am so sorry you were hurting my friend. I wish we knew. You constantly had a smile on your face and you took every single challenge that was given to you with such confidence and grace."
Paul finished the heartfelt post by urging those battling mental health issues to reach out and seek help from loved ones.
The 47-year-old actor also called on his followers to offer support to anyone who could be struggling.
"I hope whoever is reading this note that feels lost or sad or uncertain about the future please say something. Life is so damn special," he added.
"We must suffocate the noise and focus on each other. Hold each other up. That's what this life is all about. Connect with someone you care about and say I love you," Paul urged.
