First Name Basis
"Cobb cocks his head and he's moving swiftly around the dining counter, wiping off stains. Arthur off-handedly hands him the dirty cups of coffee and they soundlessly wash up breakfast.
"Personal?"
The question comes as they're watching the morning news; Cobb switching through History Channel and CNN and Arthur operating the radio to get some good quality music. Arthur's too absorbed in the dials to notice when Cobb prods his knee and repeats, louder this time, "Do you want to move because of a personal thing?""
Post-Inception, Arthur stays at Cobb's house and they become something almost like a family. Arguing kids, whipped cream fights, washing dishes, and choosing apartments. Then Arthur realizes he's falling in love.