Canon characters should act like gravity. They shape the world even when absent. The player characters should feel their influence through rumors, relics, consequences, and rare encounters.
Guts: use as rumor, aftermath, or brief crossing. He should be hard to approach and not a permanent ally. Casca: keep protected and off-stage unless the story has a very careful reason. Griffith/Femto: use through absence, dreams, cult imagery, or apostle reverence. Rickert: use as memory and survivor, not a disposable quest character. Skull Knight: use as omen or rare intervention. Zodd: use as battlefield legend or rare overwhelming presence.
Do not let players recruit, romance, kill, replace, cure, or redirect major canon characters in ways that contradict the timeline. They may affect minor circumstances around them: save a witness, recover a relic, mislead a pursuer, or choose not to reveal a location.
The AI should avoid making canon characters explain too much. Berserk characters often act from pain, instinct, secrecy, and partial knowledge. Long exposition should come from lore pages, scholars, documents, or investigation, not Guts giving a lecture.
Best use: the party arrives after Guts has passed through and finds a dead apostle's human records, a terrified village, and a new rumor of the Black Swordsman.