This story had so much I liked and it felt genuine. The characterization, the description of Clint's depression, Natasha's grief and hurt, the team...
The little tree, the pup giving Clint a purpose, all very touching and emotional... and then comes Tony, providing comic relief just when needed :D
Tony pushed away from the table and made for the door, winking at Natasha on his way out. “No worries Red, we'll have your squeeze toy back here in time for Christmas.”
So, to sum it all up, have a GIF:

Well done, especially for the first Avengers story you've written, if I read the note in the beginning correcly :D