Griffith betrayed Guts during the Eclipse, where he sacrificed his Band of Falcons to become a member of the God Hand. Despite being partners and best friends, Griffith wanted to make Guts as unhealthily obsessed with him as he was with Guts. He wanted to punish Guts and Casca both for finding happiness without him. Griffith was obsessed with Guts and relied on him to succeed in his goal of taking a kingdom. When Guts left the Band of the Hawk, Griffith was devastated and acted terribly rashly. Griffith acted in spite and wanted to take everything Guts held dear, and thats why he slept with Princess Charlotte. As a result, he was tortured and maimed.