I completely agree with this. I was afraid I was going to be a Debbie Downer, but I personally think they might have some negative associations with it. For some people the holiday can be a reminder of what we don't have, just as much as what we do have. A few years ago my dad passed away, not even around Christmas, but I always spent Christmas eve with him and since then it's really hard to get behind the holiday. Clint and Natasha don't seem like the overly Christmasy people to begin with. But they probably grew up either apathetic to the holiday, or actually not liking it because it was a reminder of the family and childhood they never had. As adults and they become more adjusted I think they might do small things together, but I think it would be gradual and still on a small scale. I definitely agree with the team statement. They would support each other and do what was comfortable for both of them.

but I think it would be gradual and still on a small scale.

Siiiigh, this seems so bittersweet and wonderful and I am in love with this idea :D And I definitely agree, Christmas could make them sad, but they could turn that around, slowly, gradually, and find their own traditions for the holiday.