How did Guts and Griffith meet?

Griffith defeated Guts in combat and recruited him into the Band of the Hawk. The terms: Griffith owned Guts until Guts could beat him. This transactional beginning conceals something genuine — Griffith saw in Guts the only person who had made him feel anything like equals, and Guts found for the first time something like belonging.

What was their friendship actually like?

Fierce, competitive, and deeply real. They pushed each other. Guts was the Band of the Hawk's greatest warrior; Griffith its leader and strategist. They were the two most capable people in their world, and their dynamic was built on mutual recognition. For Guts, it was the first friendship of his life. For Griffith, Guts was the one person he couldn't completely instrumentalize.

What broke the friendship?

Guts' decision to leave. After overhearing Griffith say that a true friend is someone with their own dream — someone you have to fight to keep — Guts realized he had no dream of his own; he was living inside Griffith's. He left to find his own path. Griffith, devastated by losing the person he'd built his emotional world around, made a catastrophic decision: he slept with the princess, was caught, and was imprisoned and tortured for over a year.

What was the Eclipse?

The Eclipse is the central catastrophe of Berserk. After the Band of the Hawk rescues Griffith (broken by torture), he activates the Crimson Behelit during a solar eclipse. The God Hand offer him his dream — the Kingdom of Midland, demonic power, everything he ever wanted — at the cost of sacrificing his companions. Griffith sacrifices the Band of the Hawk. He becomes Femto. Guts watches. There is no adequate description.

What does their relationship mean for the rest of the story?

Everything. Guts' entire journey after the Eclipse is defined by what Griffith did. His survival, his ongoing fight against apostles, his attempt to protect Casca — all of it is the aftermath of the moment the one person he trusted did the unforgivable.