My Sister Wanted My Three Mates. Her Serpent Wanted Me.

After the apocalypse turned men into Beastmen, Evelyn rescued three dying shifters and gave them everything. Then she learned they were using her to get to her favored sister. So Evelyn made a ruthless trade: all three of them for Silas, her sister's untamable serpent. But the cold-blooded outcast burns only for Evelyn—and he may be the little black snake she once saved. Now her former mates want her back, her sister wants what she has, and Silas refuses to let anyone take her again.