smooth one's / sb's (ruffled) feathers
to make oneself (or somebody else) feel less irritated or offended
Lacon was no fool, and the Cousin's wrath  just when everyone was trying to smooth their feathers was a thing to be avoided at any cost.
John le Carré: The Honourable Schoolboy.CORONET BOOKS, Hodder & Stoughton, 2000. p. 63.