(abortion, not adoption
) and yes, that is the implication.
But Lysa suggests that when Jon Arryn was the Kings Hand, she used her power to find Littlefinger, get him a place on the council and get him into her bed as her 'reward'.
This may even have started Littlefinger on the course of blackmail & manipulation himself, maybe he was blackmailed into Lysa's bed?
Just a thought
