Mouse is on edge from the moment Yates' name comes up. Voight pulls Erin into his office first, and Mouse doesn't think much of it until they come back out, Erin standing at Voight's shoulder and he can see the tension in her shoulders even before Voight opens his mouth and announces that she is going to New York. Going to talk to Yates. Mouse's chest aches. The next thing Voight says is that Antonio is the one going with her, and Mouse's gaze snaps over to Jay, can see the indignation and fear. Jay looks like he might speak, but Voight pins them all with a sweeping glare, daring them to contradict him. Jay looks at Erin, who shakes her head just slightly, jaw clenched, lips thin, eyes full of too many emotions to understand. Mouse can almost see Jay swallow his words, feels his own unease make itself at home in his chest.
Voight is getting them on the next flight out, so Mouse and Jay barely have time to say their temporary goodbyes before Erin and Antonio are whisked out to a taxi, gone before Jay can do more than hug Erin tightly in comfort, Mouse stepping in close in the empty locker room for a rare hug too, Erin giving their hands one last squeeze.
Mouse is anxious all day, feels it itch beneath his skin and its heaviness in his lungs as he struggles to focus on his own work. The anxiety spills over to the next day, and he knows it won't go until Erin is safely back in Chicago and they can put Yates behind them again.
When Voight steps out of his office and calls the unit to attention grimly, Mouse's heart drops. "Yates escaped from prison this morning with an accomplice. It's a manhunt." For a moment everything stops, Mouse can sense the unit's shock like a tangible thing reverberating in the silence. He feels sick.
The unit is clamoring to fly out en masse to New York and join the search. Voight shoots them down, saying that they won't make a difference by the time they get there, but Mouse thinks he can see that Voight wants it as much as any of them. So they stay where they are, but Voight doesn't stop them from abandoning their other paperwork in favour of following the investigation in New York, doing what they can to help. Mouse searches through security camera footage, some of which he accesses legally, and some… well, less legally. He doesn't much care. Realistically, they're not accomplishing anything; Mouse knows this. But they have to do something. They keep working until they get the call from New York. Yates is coming home.
When they arrive back that the station in the morning, Erin seems bleached of colour by stress and anger and grief. Mouse wants to gather her into his arms, wrap her in blankets on Jay's couch and cocoon the three of them there until they wake from this nightmare. Instead, he pushes back the sick feeling in his stomach and grips his NA coin anxiously while he listens to the briefing, then slides back behind his desk. He watches Jay approach Erin cautiously, knows that when he asks if she's okay, when she says that she is, it's a band-aid kind of okay. The kind of okay that really just means "lets get through this, and deal with our shit later." The kind he is intimately familiar with. So as much as he wants to pull Erin aside until it becomes a different kind of okay, he puts it aside, and gets to work.
The thrill of fear at the potential of a bomb in the station is dulled by the restlessness of being separated from his equipment, unable to keep chasing Yates. Instead, he shifts anxiously from foot to foot, ensconced in tense silence beside Jay and Erin in the midst of the crowd. He feels utterly useless when the call from Yates drops before he can get a location, and sickened when he realizes Yates has been listening in through Erin's phone. It's a horrible feeling of betrayal at his technology being turned against them so intimately. And when he finds out Yates is in Erin's apartment… He feels the sense of invasion keenly on Erin's behalf, while another part of his mind absently notes that he himself has never been to Erin's apartment. Now if he does go, it will always be preceded by Yates's shadow.
When he hears Erin coming up the stairs with unusual fervor after the team heads out, he thinks nothing of it at first. She's pissed, he knows. But he snaps to attention at the click of her fingers, and starts working on the ping furiously when he realizes what's happening. It takes a few minutes to get it, and then he's scribbling the address on a post-it and charging towards the breakroom where he slaps the post-it to the glass. Erin looks at it, then back to the phone and he watches, and knows the minute Yates hangs up. Erin meets his eyes, staring at each other through the glass, and in that moment he sees the resolve and hate in her eyes and knows he's made a mistake. His breath catches, and Erin is running, coat arching through the air as she grabs it, and he's calling desperately after her, but she doesn't pause, only throws one determined glance back at him, and then she's gone. He's shocked to stillness for only a moment, and then he's scrambling for his phone and calling Voight, spitting the panicked words through the line – "Erin's going after him alone. 34th and Sangamon." He catches only Voight's explosive "Shit!" before the line goes dead and Mouse is left in the deafening quiet of the district again.
That's all there is for long, long minutes. Quiet. Just the ringing in his ears and the fear swirling through him, choking him, knowing he let her go. Jay is the one who calls to let him know, because it's always Jay who remembers that he's there, waiting, alone. And he breathes a sigh of relief and hangs up the phone, fear extinguished. But now there's something else. The seed of a bitterness that had been overshadowed by his panic, growing. Erin, in the breakroom with Jay, only weeks ago, making a promise, her eyes meeting his, seeming to make that same promise to Mouse, never again, never again, never again, but she broke it, didn't she? She went in alone, left Mouse with his panic, left Jay and Voight racing through the streets to catch her in case she fell, she left. Alone. Knowing that she was walking into a dragon's den she might not walk out of.
They clean up the case, and he sees Jay watching Erin tenderly, and the bitterness grows, another thing Jay has forgiven before asking for an apology. He stares hard at his hands, at his papers when Erin leaves before him with Benson. Jay asks if Mouse is coming back to his place. Mouse wants to say yes, he does. But he knows that Jay won't let Erin go back to the apartment Yates invaded tonight, knows that Erin will spend the night in Jay's bed while he comforts her, and he knows that the bitterness will burn under his skin all night. He says no. He ignores the surprise and hurt that flash over Jay's face the best he can, taking their sharpness as his due. He goes home alone to his shitty apartment and lays awake for hours, and finally sleeps, falling into nightmares of Nadia's body, and Erin's blood in the abandoned halls of Yates' childhood. The bitterness burns into fury and grief.
The next day he can't bear to look at Erin, but he's pretty sure she doesn't notice, lost in her own head. Jay might, but he tries not to meet his eyes either because he can feel his emotions simmering so close to the surface he is afraid anything might set him off. He goes home and lays awake and dreams and wakes. Today, Erin notices. She throws him bewildered glances throughout the day, each one grating against Mouse's skin. He slips out a few minutes early, grateful for the escape. He nods to Platt on his way out, and is halfway to his car in the misty grey day when Erin catches up to him.
"Mouse!"
He turns automatically at her call, regrets it immediately. She jogs towards him, hair blowing in the wind, washed out by the overcast weather.
"Hey, are you coming to Jay's for dinner tonight?" She shoves her hands in the pockets of her sweater – it's chilly out here, and she didn't bring her coat. She looks up at him with doe-eyes and dark shadows.
"No." He tries to say it gently, despite the fire under his skin. She looks taken aback anyway.
"Mouse," she says imploringly, "what's going on with you? Are you okay?"
Mouse feels words writhing in his chest, rising with the pressure in his chest and he clenches his fist tightly, feeling his fingernails dig into the flesh of his palm.
"You promised." His voice is low, the kind Jay would immediately recognize as dangerous. He wonders if Erin knows it; he doesn't think she's heard him speak like this before.
"What?" Her brows draw together.
"You promised you wouldn't go in alone." His voice is sharper. Erin's eyes widen slightly in recognition.
"I'm sorry Mouse, but-"
"No. You promised you wouldn't go in alone, you promised. And what did you do? You went in alone, you went after Yates, who had already killed someone we care about, who was targeting you specifically, you went after him alone just like he wanted, and you left me standing there alone! Waiting for someone to call me and tell me that you were dead!"
"Mouse-" Erin tries to interrupt, looking not a little shellshocked, but the words are tumbling out unbidden, his voice rising till he's practically shouting and he's distantly grateful there's no one else in the parking lot.
"You have no idea what it's like sitting it the district every day, knowing at any moment one of you could get shot, or killed, and I can't do a god damned thing about it! But at least I know that you have each other's backs, because you don't! go in! alone! You promised, and then you did it anyway! It was bad enough being in love with one reckless idiot, I don't know what the fuck I did to deserve loving you too!"
Erin is standing there wide-eyed and pale, and his chest is heaving and he's so angry that it takes a moment to realize exactly what he just said. He freezes, every part of him going cold, eyes wide, shit, shit, shit. Erin moves like she's going to step toward him, and he stumbles back whirling around and striding to his car, falling into it, fumbling with the keys and reversing out of the parking spot. As he drives out, he catches sight of Erin in his rear-view mirror, still standing exactly where he left her, without her coat, in the cold.
It takes until he closes the door behind him in his apartment for his brain to really catch up with what he's done. What he's ruined. Because he has, ruined it. His mouth spewing out words he had never let himself consciously realize, words that should never have been spoken. The three of them had been balancing on a delicate tightrope, and he just shoved them tumbling off.
He takes off his coat and his shoes and puts his things away robotically, mind foggily replaying his own words in his mind, replaying that first night in Jay's apartment when Erin asked if he loved him. He makes dinner and eats it and goes to bed hours before he usually would. Turns off the light and lays in the dark wrapped in blankets and feels the pressure in his chest that isn't anxiety. Not this time. It's grief, for everything he has just lost with a few careless words. The tears drip slowly from the corners of his eyes until sleep comes for him from the shadows.
