Mister Lonely Heart is a changeling "Grievance Councelor", who imitates ponies that his clients have problems with. Applejack wants to say a few choice words to a relative. A dead relative.
Mister Lonely Heart is a self-styled "Grievance Counselor", a changeling who mimics ponies that his clients have issues with. When Twilight Sparkle pays him a visit, he finds out how painfully neurotic the Princess of Friendship really is.