[Nicholas] made a grilled cheese for his son [Glen]. [Glen]'s brother [Michael] ate a salad.
('Nicholas', 'Michael')
[Nicholas] made a grilled cheese for his son [Glen]. [Glen]'s brother [Michael] ate a salad.
[{('Nicholas', 'son', 'Michael'): [('Nicholas', 'son', 'Glen'), ('Glen', 'brother', 'Michael')]}]
['son', 'brother']