Tony Stark Meets an Extremely Unimpressed Time Traveler, or, Thomas Barrow Makes a Surprisingly Good 21st Century Butler (слэш)

In which Tony Stark ditches a boring party, makes an addition to the household staff, throws a much better party, and tries not to sexually harass his new butler.
Or,In which Thomas Barrow has a little trouble getting home from the pub, is generally unimpressed with many aspects of the 21st century, never thought of himself as a conservative dresser before, and may or may not be falling in lust with his new employer.
tl:dr: Thanks to time travel, Thomas Barrow becomes the Avengers' butler.