Okay, so the Wiki and one of the authors say a that Whitestorm is Brindleface's mate but it never fit with me. It's out of character for him to leave his kits to fend for themselves, even if he's fallen out of love with Brindleface. And queens aren't required to tell who the father is, but Whitestorm didn't raise Ashpaw and Fernpaw, didn't even really interact with them as kits. So if he was their father, he was really bad at it, which, he has more kits that he's good with so that might not be the case, OR Brindleface is ashamed of her kits' father and didn't want to associate them with him OR it was a one-time thing.

I personally headcanon that Darkstripe is their father. I saw it in a story once and it made sense. What do you guys think?