The Insectivore (http://archiveofourown.org/works/584754) by antistar_e is my go-to MCU daemon fusion; it's basically a retread of Thor through some time before Avengers-ish but with daemons, centering on Thor with a side of Clint and some Tony as well, from Darcy's perspective.

There's also And Let The Future In (http://archiveofourown.org/works/1182350/chapters/2450476) by ashen_key, which has separate chapters for a few characters, including Clint, Nat, and Thor.