User blog comment:Waterwecna/Things I did not get about The Kindness of Strangers/@comment-3131129-20121210160615

Finna killed herself because she was the only one (apart from Gaius) who knew who Emrys was. By killing herself, she protected that secret, which she was destined to do. That is why Morgana asked her: "Who is Emyrs" (or something along those lines), because she knew. In a way, Finna was mocking Morgana by killing herself, expressing that Emrys/Merlin is worthy of that sacrifice because of the great things has has/will do.