Steve:
Why: You two are celebrating something
What: Large vanilla shakes at a diner down the street
Bucky:
Why: You two were out drinking with your friends, and were starving when you got home
What: Girl Scout cookies that were still on your counter from when you bought them earlier that day
Pietro:
Why: He couldn't sleep and got bored, so he started cooking
What: Homemade Mac n' cheese that he made
Loki:
Why: You had a late work night and forgot to eat dinner before going to bed.
What: Cupcakes Loki had baked for you two while you were at work.
Clint:
Why: He got home late from a mission
What: Bag of potato chips he picked up on the way home
Thor:
Why: He was hungry, of course.
What: Poptarts
Tony:
Why: You needed cheering up
What: Burnt pancakes that Tony made
Natasha:
Why: You couldn't sleep
What: Peanut Butter Sandwich
Wanda:
Why: You had a rough day at work and needed comfort food
What: Ben and Jerry's

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Avengers Preferences
RandomPreferences for Steve, Bucky, Pietro, Loki, Clint, Thor, Tony, Natasha and Wanda *Sorry I didn't do them for Bruce. I was having a particularly hard time writing for/about him and I didn't think I could do him justice.