Title: Fidelity
Rating: E
Pairing(s): Initial Arthur/Gwen, end-game Arthur/Merlin, Gwen/Lancelot.
Current Length: 50,943 words.
Warnings: Consensual infidelity, descriptions of physical injury and illness, magical consent issues (non-sexual). See tags for further details. Additional warnings in relevant chapters as the story progresses.
Summary: Canon era AU. Arthur and Gwen have been married for a little under a year when Arthur discovers Merlin's magic, and suddenly everything changes. In a desperate attempt to regain the King's trust, Merlin offers to do the only thing he can think of: to voluntarily bind his power, and with it sacrifice all hope for a united Albion. But as with all things magical, such a concession comes with a price, and with an assassin in their midst and a vital political alliance hanging in the balance, Merlin is not the only one who will find his loyalty tested.
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Fidelity on AO3 )