[Boaz]

Petry Baelish is Lord of Harrenhal and Lord Paramount of the Trident. The latter means that the Lannisters have demoted the Tullys and promoted Littlefinger as overlord of the Riverlands. Since Littlefinger has no interest in getting himself either killed or involved in the political and martial quagmire of the Riverlands, he's contenting himself with being Lord Protector of the Vale, i.e. he's the ruling Regent until Robert comes of age... which Littlefinger will never allow to happen. Also, since Lysa acknowledged Tommen's legitimacy the throne was obligated to return the title of Warden of the West to the Arryns... ergo Petyr Baelish is also Warden of the West.