Who is Keenan from Wicked Lovely and what is their importance?

Keenan is the Summer King. His power was bound by his mother and the Dark King, making him powerless when compared to another faery monarch. Keenan's curse is that he must always choose a human girl, who will then become a faery. If she chooses the test of the Winter Queen's staff, then she with either be his true queen, or the Winter Queen's chill will fill her, driving out all warmth. She will then try to convince any girl in the future not to trust Keenan, and can only be freed when another girl does choose to take the test. If Keenan's chosen does not choose to take the test, she will become a summer faery, one of the Summer Girls, and be a member of his harem.

Keenan longs for the day he will find his Summer Queen, and with each girl he hopes that she is the one. Keenan has a volatile temper, quick to flare up, but then quick to die back down. He is arrogant at most times, sad and lonely at others. Keenan is single minded in his quest to find his true queen and convince her to take up the staff.