Five Surprising Signs He's Hooked:
He calls you by the wrong name.
You've met all his friends.
He remembers more about your life than you do.
He's not out on the town as much.
He cares if there's air in your tires. Or whether your work parking lot is well-lit. Or whether you've got enough OJ when you get the sniffles...
One:
Nicknames were Derek's thing. From Baby and honey for the girls whose names he couldn't be bothered to remember, to Case, Space-Case, Klutzilla, and Keener for the one girl whose name he couldn't get out of his head. He tried, always unsuccessfully, to replace her name in his head with those of the many girls he serial dated his first few years at Queens, but nothing really worked and his feelings for her gradually progressed from completely platonic step-sibling toleration to love, and long-term relationship, in the most serious type of way.
Casey hated nicknames, always had. She'd never had much luck with names either—Derek as Ralph and vice versa—but nicknames, particularly the ones Derek called her, were never her cup of tea. She could have chalked it up to feminism, but her ideals really had little to do with the names being called, and everything to do with the one doing the name calling. She tried retaliating with the obvious: "DER-EK!" but when that produced no results, she simply gave in and acknowledged her worst fear: she was in love with Derek.
Luckily for everyone, awkward encounters, heat-of-the-moment decisions, and fights so full of frustratingly tangible unresolved sexual tension that even George noticed, were their thing, and, once both realized their irrevocable and unarguable attachment to the other, things went smoothly from there. Actually, they didn't. And that's the point; they got together their junior year of university (finally!), but the road to happiness is never easy, and they struggled.
Dasey had their ups and downs, but they've stayed together through it all. What Casey can't deal with, however, is the sudden reappearance of Sally in their lives. Not that she showed up demanding Derek back or was a constant throughout their entire relationship, but the fact that she was between Casey and Derek, yet again, was nothing short of annoying.
The first time it happened, Casey, and Derek for that matter, was shocked. He asked her to hand him the remote so he could change the channel from her show: Dancing With the Stars, to his: Hockey, but accidently called her Sally. Casey handed him the remote and was so surprised that she didn't even complain that he was stealing the TV. And, of course, being how she is, Casey over analyzed every aspect of their relationship, dating back to the first time they met, that could possibly make her remind Derek of Sally. She came up with nothing.
The second time was equally as shocking, though not nearly as mundane; Derek and Casey were at a Leaf's game for Derek's birthday and he had just introduced a friend of his on the Leaf's team to his girlfriend, interestingly named "Sally… er, I mean, Casey, McDonald." He slept on the couch for a week.
When it happened again, Casey was prepared. She had even made notecards explaining why, if Derek was so preoccupied with Sally all of a sudden, Casey needed to break up with him. Derek called her over to him at a party to ask her when she wanted to leave, called her Sally on accident, and subsequently lost himself a girlfriend.
Casey, in tears, pulled out her notecards, and began reading them off one by one, while Derek stood their helplessly and the entire population of the party watched eagerly. After she reached number six of ten, Casey couldn't take it anymore, and just broke down.
"I love you," she told him despairingly, "and that means that I want to see you happy. And if you being happy means you're better off with someone else, go to Sally with my blessing."
Derek just stared at her.
Then he replied, "Casey, me being happy means you being happy. Actually, me being happy means you; what Sally and I had was great, but what's between us is so much more than that. I love you, not Sally or anyone else, only you."
Casey looked up, tearfully, and asked him, "Then why the name mix-up? Are we that similar to you, like I'm replaceable with the next available brunette who comes along and is willing to date you?"
Derek looked momentarily perplexed. "I have a hunch, but I honestly don't know. All I know is you are the only girl for me, and I'm serious about you, Casey McDonald."
Casey sighed deeply, for appearances, and, seeing he would get on his knees and beg if she wanted him to, took him back. She hit him once on the chest for his name confusion, gave him a quick, chaste kiss on his lips, and flounced out of the party, clearly indicating that she wanted to leave.
Derek thought of all the names he had called her, good or bad, touched his lips where she'd kissed them, as if her touch left a trace, and decided that beautiful was the only name she deserved.
To Derek Venturi, Casey McDonald is addictive, and he is hooked.