The story requires that Miles have a broken heart. It’s how he and Iris bond. He’s such a cheerful person, though, that it’s disconcerting to see him feel sad. His spontaneous personality — singing loudly in the video store, offering Christmas fettucine — seems impervious to depression.
Miles finds so much joy in his daily life that I want to call him a Seven. His songwriting and film scoring work bring him pleasure. Being tossed into the middle of Arthur’s dinner party brings him relaxation. Although his girlfriend cruelly dumps him, he finds a way to move past her without lingering or wallowing. Life is too exciting for Miles. He won’t be bogged down by sorrow.
It’s hard to separate Miles from Jack Black. The actor’s real life personality infuses any character he portrays. Dewey Finn from School of Rock is also impulsive and bold. Miles is a dependable adult unlike Dewey (lol), but they share an authenticity. What you see is what you get. Black’s style meshes well with Miles’ happy Seven qualities.
He also meshes well with Iris’ Two. She doesn’t need more drama in her life, and Miles is low maintenance. He’s easy to love: expecting nothing and welcoming everything.