So, how does Birchface feel about accidentally killing 3 kits with his false sign? Cause that would be something hard to live with...and would he have been thrown into the dark forest had Starclan found out? Also, if does BB!Mapleshade's story follow cannon where it's his sister that assumes it's his kits and Maple just keeps quiet? Cause if so, he shouldn't be mad at Maple for it tbh.
How does Birchface feel about his false sign killing 3 kits?
He played a stupid game and won a stupid prize. He made the sign in a fit of anger, wanting to warn Frecklewish that they were the kits of his murderer, and then watched his dad exile them and lead to their drowning.
He got what he wanted and lives in constant guilt over it, knowing that if he comes clean, they will probably chase him out too. He got his sister damned for his stupid, cruel action.
Does BB!Mapleshade's Story follow canon?
It follows canon completely until the moment that Mapleshade is bringing them across the river. The two major changes are that there is NO HUMAN BRIDGE she could have taken, and also she doesn't have grief delusions of her kits telling her to kill.
She allowed Frecklewish to believe they were Birchface's kits, and that enraged him. She was using his sister to shield his killer's spawn in their midst, he saw those kittens like brood parasites and lost sight of the fact they were children.
A lie by omission is still a lie, in his eyes.
It didn't hit him that he got what he wanted until RiverClan fished three tiny bodies out of the river. He didn't think about how sick his desire had been until he was watching Darkstar refuse to let Mapleshade lay her babies to rest.
I like to think of MV as a story with no heroes. Everyone is at fault for something here, and the only innocent people were the kittens they failed to protect.