Possible Clues:

• Author of 28 19 in English river junction
• When doubled, a Nabokov protagonist
• Literary villain, one requesting a lift across northern suspension bridge, heading for trouble
• See 18
• With 37-Across, narrator of 'Hitchhiking With Lolita'?
• River junction suggested by Nabokov protagonist
• A major character (with royal connections?) of Cooper
• When doubled, a literary lecher
• Literary character with the same first and last name