A Seventh Son will receive "the last heritage, the pauper's portion" and is often called a "pauper son" because of this. Certain seventh sons receive special rights and powers such as the second sight, alternatively referred to as the "twain sight." These rights and powers put them on a similar level to the FitzFaeren.
It is not clear in the 100 Cupboards trilogy why certain seventh sons inherit these rights and powers, while others don't. However, the idea of a seventh son inheriting special powers comes from folklore, in which only the seventh son of a seventh son inherits these powers. It could be then that in 100 Cupboards only seventh sons of seventh sons receive the second sight. This is consistent with Henry York's case, because he is the seventh son of Mordecai, who is also a seventh son.
- "To many ones [it means] nothing. It means they were the seventh-begotten son, that when their father is put to grave-sleep, they shall receive the last heritage, the pauper's portion.... To others, to you, to me, it is potens. It is the twain sight, the second seeing."—Darius, p. 77 Dandelion Fire.
- "The sevenths, especially the green men, are like man-faeries."—Fat Frank Faerie, p. 296 Dandelion Fire.
- "[Green men are] seventh sons that are connected to growing things. Green things. Like your dandelion."—Monmouth, p. 296 Dandelion Fire.