What he wanted was a challenge on the part of Nikolay Vsyevolodovitch, as he had not himself any direct pretext for challenging him.

His secret motive for it, that is, his almost morbid hatred of Stavrogin for the insult to his family four years before, he was for some reason ashamed to confess.
And indeed he regarded this himself as an impossible pretext for a challenge, especially in view of the humble apology offered by Nikolay Stavrogin twice already.

He privately made up his mind that Stavrogin was a shameless coward; and could not understand how he could have accepted Shatov's blow.

So he made up his mind at last to send him the extraordinarily rude letter that had finally roused Nikolay Vsyevolodovitch himself to propose a meeting.

Having dispatched this letter the day before, he awaited a challenge with feverish impatience, and while morbidly reckoning the chances at one moment with hope and at the next with despair, he got ready for any emergency by securing a second, to wit, Mavriky Nikolaevitch Drozdov, who was a friend of his, an old schoolfellow, a man for whom he had a great respect.