Gibson and Ledger got along right away. “God, when I first appeared on set, I was really shaking in my boots, but he just put me at ease right away,” Ledger recalls. The young actor has a lot of suspenseful energy, and the “Braveheart” star taught him how to relax. “He’s really just an ordinary person,” Ledger insisted.
Ledger’s co-star was “such a gentleman”, leaving him “pleasantly surprised.” Ledger explains that “not everyone in his position is as friendly as he is”. While filming “The Patriot,” Ledger was refreshing with his breakout role in “10 Things I Hate About You.” Working with Gibson “was a huge step in my life and my professional career,” Ledger admitted in a television interview (via Midsummernina). However, he found that Gibson was “completely normal” despite his “superstar”.
Sadly, the two actors would fracture in their relationship a few years later. When Ledger was offered the role of Ennis del Mar in “Brokeback Mountain”, Gibson encouraged him to decline, New York Daily News was reported in 2008. Gibson seems to think this part will ruin Ledger’s career. Ledger went against Gibson’s advice and still joined, costing him his friendship with his former co-star. He even said that the role was “a reaction against the comparison that I’m the new Mel Gibson.” Their relationship never recovered after that, but Gibson grant a regretful statement after Ledger’s death, lamenting that “should have called him years ago.”
Their relationship may have turned rough in the end, but Ledger still learned a lot of valuable lessons from his on-screen father. Without Gibson’s guidance, Ledger might not have become the Oscar-winning actor he certainly became.
https://www.slashfilm.com/938038/filming-the-patriot-with-mel-gibson-taught-heath-ledger-a-valuable-lesson/ Filming the Patriot with Mel Gibson taught Heath Ledger a valuable lesson