Dusa

Dusa is a shade in the form of a floating, disembodied Gorgon's head. She works as a maid in the House of Hades, constantly floating around and cleaning.

Affinity
If given Nectar, Dusa will give you the Harpy Feather Duster.

After being given 6 bottles of Nectar, further gifts will be locked until her favor is completed.

Completing the favor and gifting her a bottle of Ambrosia will have her give you Companion Fidi in return.

Dusa's affinity gauge is maxed out at 10 hearts, requiring the gifting of 6 Nectar and 10 Ambrosia, differing from other romanceable characters. Further information detailed in Romance.

Favor
Dusa's favor involves the lounge renovations, which she has fallen behind on doing. Zagreus must help her bring the lounge up to Nyx's standards by using the House Contractor to complete a minimum of 12 Lounge-focused renovations, which must include at least one rug for the area as well as cleaning up Cerberus's fur and the scratches he left in the floor. Doing so will complete the A Place of Revelry prophecy and unlock the ability to give Ambrosia to Dusa.

Romance
Dusa's romance differs from the other options in that each successive gift of Ambrosia requires an increased number of bottles; while her first only requires 1, subsequent gifts require 2, then 3, until her final gift is given as 4 bottles.

After giving Dusa the tenth gift, she and Zagreus will have a conversation where Dusa explains that she has come to realise she isn't looking for an intimate relationship, and isn't attracted to him in that way. They agree to remain "friends for all eternity" instead, though as Zagreus points out, that in itself can be its own form of love.

Some time after the final romance conversation, Dusa will offer to return all the Ambrosia she has been given; Zagreus may take them back or persuade her to keep them as the gift they were intended as, with no negative repercussions for either choice.

Dusa can be romanced at the same time as Megaera and/or Thanatos with no drawbacks.

Quotes
"For quotes and dialogue regarding, please refer to /Quotes."

Additional notes

 * Dusa's position as a maid in the House of Hades is a play on the name Medusa - she is Maid Dusa.
 * The secrecy around Dusa's former life and her claims that she was a very different person when she had a body imply that she might very well be the head of the infamous Medusa.
 * She seems to have a crush on Zagreus, emitting a gasp and several hearts whenever he gets close. Her conversations are short and flustered, and she often flees into the rafters afterwards. As of the Long Winter update, this relationship can be explored in further detail.