Monochrome

Monochrome had a brother, once. His name was Oblivion, and they were as thick as thieves, both raised as warriors, spending nearly all their time together, either training or exploring. Separately, they were as deadly as reapers, strong and silent and terrifying. Together, they could have beat a god.
When Monochrome found Chasm and nurtured something that would become a very deep love, Oblivion stood by his sister's side. He liked Chasm, truly, and even if they would go on to lead their own pack, have their own pups (which, they would, in time), they wouldn't leave him behind. Monochrome loved her brother like the moon loves the sun.
Fate is a twisted master though.
Oblivion would die without much fanfare. Two wolves would take him by surprise as he woke, and for all his lethality, he'd fall to their teeth. Monochrome would kill both of them in a rare bout of genuine rage, despite being heavily pregnant. She'd never been the sort to kill slowly, she knew how to bite for lethality and did it. But this once... She let her brother's murderers bleed out from small wounds.
She mourned for a long time after that. Even with Chasm at her side, she felt hopelessly unmoored without Oblivion. Monochrome did not know how to exist as one half of a coin, felt the loss of her brother like a physical pain. When her first pups came (Two of them, a boy and a girl just like she and Oblivion had been), she was inconsolable. She loved her son and daughter beyond reason, loved her pack, loved her mate. She was a great leader. But for much of their puphood, Wander and Aubade found their mother to be distant, sad, and quiet.
By her second litter... Monochrome was better. Three pups this time, one of them bearing her brothers name (and his looks, she would realize, as he aged), all who found their mother to be bright, willing, and kind. Their older siblings, now established hunters, found a mother where there had once only been a wolf who bore them.
Monochrome will likely always be a melancholy wolf. There will never be a time when she does not turn to look for her brother, does not allot for the space of him at her side. When the Blue Moon rises in the west each month and her sleep brings her to the Dreamlands, she sees him, a wisp of a form with the same wild grin in the trees. And if she comes back from that surreal place with a smile on her face, even as she bleeds from numerous wounds, nobody says anything about it.