Having just watched Hayao Miyazaki’s movie version of “Howl’s Moving Castle”, I just thought I would recommend a good chunk of Miyazaki’s films as great source inspiration for Sorcerer, some of his work being textbook examples of Sorcerer rituals and relationships.

While his work is not always as dark and intense as your typical Sorcerer campaign and perhaps a bit more on the whimsical side. But here are a few examples:

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Howl’s Moving Castle

Of all of Miyazaki’s films, this is the most simple and clear of all demonic relationships: the Wizard Howl has summoned and bound a demon fire (“Calcifer”) that descended from the heaven’s and now uses the Demon as the arcane power source for his impressive castle that moves about the land. We even get a flashback to the original binding roll! The demon has Howl’s heart/soul yet desires to be released from his relationship. We see that the demon “Calcifer” has been bound or contained within a fireplace and we see Howl’s own battles with his humanity and his gradual change and evolution as he starts to succumb to his own lowering humanity.

I’m reading through the novel now for comparative purposes, and it does seem a bit different. I might post it a bit later.

Castles in the Sky (Laputa)
This one is much simpler, but a young man discovers the ancient floating citadel and its automaton golems that he binds or pacts with.

Spirited Away
We’ve got Pacting and Binding with coal spirits, the Exorcism of a “demon” taint afflicting a dragon, the binding of secondary characters. I can easily imagine the entire bathhouse being a Giant Demon on its own.

Nausicaä (Manga)
This is probably one of the strongest candidates, which I’ve done a write up of at rpg.net here. It’s a great example of demons and rituals, with some great demon like creatures: giant insects from a poisonous forest, monstrous and immensely powerful technological demons from before the ecological apocalypse, including giant war gods and a massive sentient and brooding crypt brimming with forgotten technology and a secret agenda, psychic characters, bio-engineered warriors from before the apocalypse, and astral selves. We’ve got nearly all the rituals: Pacting with giant insect demons, Banishing of astral spirits, Summoning and Binding and Contacting of Spirit Demons and Giant War Gods, and the Containing of the Giant War Gods. Otherworlds! The Forest and the Inner Forest that we explore within Nausicäa’s mind. While reading the manga, you can actually see points in which the humanity rolls are called for!

I'm always on the lookout for inspiration for games, so if you get a chance, check out Howl's Moving Castle. I also get the impression from what I've read so far that Diana Wynne Jones' novel would be great inspiration for the Black Forest S&S setting.