The Whalestoe Letters (2000) by cult author Mark Z. Danielewski is an epistolary novella which more fully develops the literary correspondence between Pelafina H. Lièvre and her son Johnny from 1982-1989, characters first introduced in Danielewski's prior work, House of Leaves.
The letters are included in the second edition of House of Leaves, in Appendix II, under the name E - The Three Attic Whalestoe Institute Letters, although the companion piece includes eleven additional letters not found in House of Leaves.
Read more about The Whalestoe Letters: Plot Introduction