Having played himself into a position of power with Cersei last week, he begins stripping her of it here, as he delivers his gift to Lady Olenna, Lancel, who he had a brief run-in with previously. This leads to Cersei's arrest, and another victory for the team of Petyr Baelish and Olenna Tyrell (now 2-2). Quite how it plays into whatever his ultimate end game is remains to be seen, but if hes keeping the Queen of Thorns onside and getting Cersei out of the way, his path there is a lot clearer.