I had to write a Serious Essay about 'Manfred' as well--much more fun with merlot, and I still got an A! In re 'Frankenstein', I'm sure you know the story of how they all holed themselves up in (Percy and Mary's villa, I believe?) and did nothing but go mental on opium and talk about the occult, which led to a book writing challenge, from which sprung 'Frankenstein' & Polidori's 'The Vampyre.' As 'Frankenstein' was initially anonymously published, I've no doubt Percy aided her in the editing (& I've read things which back this up).

I'm not sure about Byron helping to edit, but I do know Byron & Percy Shelley often shared (sometimes scathing) reviews of each other's works, which then, obviously, led to many, booze-fueled make-out sessions.

I actually DID encounter Byron/Keats once, which may have traumatized me for all times. I was aghast. "Keats would NEVER!" I said. My friend was all, "Yeah, but are you SURE." But Keats was both appalled by Byron's rudeness and of his harsh criticism of Keats's work, while Percy championed him and was a great support to him, so that, at least, is possible.

I also think Percy would be a total tease, like, all sprawled out on Byron's bed one evening, and going "Oh, my Lord," when Byron walks in, with his eyes all dilated and his lips red. And. I need to stop, don't I. (...Don't I?)