As night fell, the promised storm blew up around them. Spray from
the high waves splattered the walls of the hut and a fierce wind
rattled the filthy windows. Aunt Petunia found a few moldy blankets in
the second room and made up a bed for Dudley on the moth-eaten sofa.
She and Uncle Vernon went off to the lumpy bed next door, and Harry
was left to find the softest bit of floor he could and to curl up
under the thinnest, most ragged blanket. (Harry Potter and the
There’s some vagueness in the sentence: (1) ‘left’ seems like a predicative complement for Harry, and ‘was to’ means ‘was obliged to’. (2) to-infinitive clause means the result of ‘was left’ –– Harry was left and he found ~. Which one is right or is there some meaning otherwise?
The major dictionaries don’t seem to do a good job covering this sense of leave, but to leave [someone] to [do something] means roughly “not to take care of [someone], such that he/she must [do something]”. For example:
[…] his friend and lord had not kept him informed about these important events but instead had left him to fend for himself; left him to die, probably. [link]
For a time he was left to find his own way, to set his own standards. [link]