My most lovely granddaughter,
I hope dearly that you are able to soon read this letter. I have been told by my son, your uncle, that your cousin Marius has proven himself a Squib. I believe you know that he is a year and several months younger than you and should have received a letter inviting him to attend Hogwarts in the recent past. Unfortunately, the day is nearing the first of September, and Marius has yet to receive his letter.
I write you to warn you not to speak to Marius. I do not know of the state of your relationship with Marius in the past, but even if you two have been attached at the wand arm for your life, I do not want and nor do your parents and family want you to converse with him. Marius will be taken away from our family.
I know that this may be stunning to you, and, should you have had a decent relationship with Marius, this may be difficult to execute. But Elizabeth, should you fraternize with him, you will, too, be disowned.
Sincerely, your grandfather,
Phineas Nigellus Black