Get it? Because Yellowfang is his mother?
Here is Brokenstar, in the Dark Forest, with his back turned to Yellowfang, in StarClan.
Yellowfang and Brokenstar are some of my favorite characters: they both went through a lot— Yellowfang was a medicine cat, therefore prohibiting bearing kits, yet she had kits with Raggedstar (that was his name, right?). Sadly, two died at once, but one managed to live: a little tabby tom with a crooked tail...
And a heart of fury.
He had to be given to a queen, Lizardstripe, who showed nothing but disdain for her own children and Yellowfang's kit. Yellowfang named the kit Brokenkit and not just for his tail, but also his mother's broken heart.
Brokenkit grew up constantly bullied and looked down upon, and Yellowfang would always be by his side. Brokenkit, however, seemed to see Yellowfang as nothing more than a foolish medicine cat.
He didn't know she was his mother.
Brokenkit eventually became Brokenpaw, then Brokentail...and killed his father and tried to kill Yellowfang. He seized ShadowClan's title as leader and trained cats far too young, and was a horrible cat in general.
He launched an attack on ThunderClan (and I believe he, or one of ShadowClan, killed Spottedleaf), and was quite defeated. Yellowfang took him to the medicine den, after blinding him.
Eventually, Yellowfang fed him deathberries and killed him while she admitted she was his mother. Yellowfang, quite a bit later, died of smoke inhalation.
Sorry about the fields of StarClan being so empty °^°
Darkness Only a Mother Could Love