4) Dark
Karen Vick always remembered the day that Shawn had joined the team.
She had known he was lying, she had known there was no way he could be psychic, but the important thing was that she was a woman and only Interim Chief, and she was pregnant and getting threats from higher-ups who said that she should drop certain cases, and solve some cold ones, and she was being overwhelmed, and all she needed was a miracle.
Or at least a facsimile of one.
Shawn didn't know her, but she knew him. She had known of Henry's son, in her capacity of his partner. By that time, Shawn was gone, on a road trip of all things, but she still learned. She had learned about the poker games, where Shawn used to clear the whole force of all their cash, and the interrogation rooms, where he would witness his dad interrogate someone from behind the mirror, then walk up to him and make a statement: "He's guilty," which always turned out to be right. She'd even learned that he'd been arrested by his own father, and spent the night in the holding cell singing commercials at the top of his lungs.
She remembered all of it, and she knew he wasn't psychic. What he was, though, was someone who could help her, and that was all that mattered.
So she put him on her toughest case, and sure enough, it was solved within days. She kept him around, and tolerated Lassiter's complaints and O'Hara's occasional looks, because of two reasons.
She remembered, and Henry had supported him.
And yes, she also tolerated Shawn's insane 'visions' because she knew that it wasn't one of those things you could just stamp down; Shawn wasn't one of those things. Shawn was the kind of guy who was always there, always annoying you, always loud, always unruly, always…
Except when he was gone, the place just seemed a little… dark.
And Karen Vick knew, all too well, how working in a police station, especially certain areas, could slowly bog down a person, could cause them to stop believing things could turn out okay, and no amount of help from 'outsiders' would ever be help, because they didn't know what you went through…
Henry had helped her through that. And now Shawn was there, overly ridiculous and crazy, but amusing and always cheerful, and she knew that the previously serious station would never survive without him. Especially not her Head Detective and his Junior Partner.
Because you can't just show someone how good something can be – how cheerful, how happy, how light – and then take it away. It's much worse than never having it.
So Karen Vick remembers, and she's always a little less harsh than Shawn maybe deserves, and she lets him try to barge in on all her cases, and she always smiles a little when she can see or hear him through her door.
Because the station would be dark without him.