making the 2nd or later book in a series free

[DrNefario]

Originally Posted by DNSB

As an example, Lois McMaster Bujold's Falling Free was serialized in Analog magazine (Dec. 1987 to Feb. 1988) while it is part of her Vorkosigan Saga series since it shares the same fictional universe and the quaddies made appearances in other Vorkosigan Saga stories.

Also quite a good example of a book that does not need to be read with the rest of the series. Some people insist on starting with this one because it is the first in the chronology, but it is very tangential to the Vorkosigan saga and not very representative. And there is nothing in it that you need to know. Maybe better to regard its place in the wider series as an Easter Egg.