The "Regarding Rupert" challenge:

Due to the Nth head trauma (or maybe a spell, or something else...it's all up to you), Giles' life and the Scooby's changes drastically.

Not only has he lost his memory, but even his faculties and his personality have been affected. In other words...the stuffy, repressed, emotional marathon man becomes "huggie guy", innocent like a child but still fiercely protective of his "family", especially Buffy. Naturally, trying to protect a slayer places Giles in a great deal of danger, so the Scoobies have to protect him from harm.