I think there's a bit on this in the Hester Stanhope biog, will check when I get home (they met when she reached -I think- Athens, they didn't get on, each presumably thinking that Athens wasn't big enough for both of them. Byron had a boy in tow at the time)

Incidentally I've always been of the school that thinks the "mad, bad and dangerous to know" epithet is a bit unfair. Look who it's coming from, for one thing (Stanhope had her pegged right too). For another, his record as an active parliamentary member of the House of Lords was rather good and his part in the Greek war of independence was extremely level-headed. And extended to doing his best to prevent a Greek massacre of Turks.