"Arsenal's a lovely place—welcome aboard," Kai said with a quick grin, extending his hand.
Normally, the captain would greet a new signing, but with Vermaelen sidelined, Kai had taken on the job himself.
Shkodran Mustafi—broad-shouldered and nearly Kai's height—shook the offered hand a little tentatively. The German centre-back had just arrived from Sampdoria. Two years older than Kai or not, the younger man's presence carried far more weight.
One was already a rising star in Europe's defensive midfield ranks; the other was still proving he belonged. There was no real comparison.
And Mustafi had heard the whispers. Wenger had quietly shared a few of Kai's stories around the dressing room. It left the newcomer just cautious enough.
From a few steps away, Arsène Wenger watched them and then, almost out of nowhere, said, pointing towards his stubble, "Thinking of growing a beard?"
Kai blinked, instinctively touching his chin. "Still contemplating."
Wenger gave his thoughts. "I think you should go for it. Adds presence."
The idea was oddly tempting. Kai might have the frame of a seasoned pro, but his boyish face sometimes undermined the intimidation factor.
As they headed down the corridor, Kai asked Mustafi, "Any secret to growing a thicker beard?"
Mustafi thought for a moment. "Honestly? Just shave more often. Some lads use growth serum if they're desperate."
"Hair-growth serum? That even works?" Kai raised an eyebrow.
"It's Europe," Mustafi said with a shrug. "Plenty of bald people. They take hair seriously. I've got a bottle at home—I'll bring it tomorrow."
Kai chuckled. The gesture wasn't lost on him: Mustafi was making an effort to fit in, and winning over the locker room vice-captain was a smart first step.
Back in the dressing room, Kai called across the room. "Laurent, meet your new partner."
Laurent Koscielny looked up, then at Mustafi, then back to Kai. Only when Kai gave a small nod did the Frenchman step forward.
"Laurent Koscielny," he said.
"Shkodran Mustafi," the newcomer replied.
Kai went on to introduce Mustafi around the room, and with his stamp of approval, the integration was smooth. No one was about to make life hard for a player personally welcomed by Kai.
.
On the pitch, Mustafi was beginning to understand what the reports meant. Arsenal's reserves tried probing through the centre, but Kai's presence was like a movable wall. They were forced wide time and again, only to find the big midfielder still covering ground.
Then came the scare. Mustafi misjudged a header and stumbled, watching helplessly as Rosický burst toward the box.
That's it, he thought.
But a blur of red came across his vision. Kai thundered in, shoulder-to-shoulder with Rosický, knocking him off balance. Without breaking stride, he leapt, hung in the air, and nodded the ball clear—core strength and timing on full display.
Mustafi's jaw dropped. Is this guy even human? he wondered.
Kai landed and immediately turned, eyes blazing.
"What are you doing?" he barked, striding over. "Stay switched on! Training or not, you play like it's match day."
When Kai finally stalked off, Mustafi pushed himself up, brushing dirt from his shorts, his expression tight with frustration. Being shouted at on his first day wasn't how he'd imagined things.
Laurent Koscielny jogged over.
"Don't take it the wrong way," he said evenly. "He's doing it for your own good."
Mustafi glanced up, still frowning.
"I don't know about other clubs, but here in Arsenal," Koscielny continued, "training games matter. They decide who starts on the weekend. Even beyond that, how you train shows in real matches. If you switch off here, people wonder if you'll switch off when it counts."
"I wasn't slacking," Mustafi protested.
"That's the same thing," Laurent replied with a small shrug. "Zoning out is slacking. The Premier League moves fast. Kai's right—you have to stay sharp every second. He's already shielding you in front of the back line. If you can't settle in with that kind of cover, you've got to look at yourself."
Mustafi exhaled, the fight draining out of him.
"I get it," he said quietly, a hint of grievance still in his voice.
Koscielny offered a reassuring nod but said no more. Around here, actions spoke louder.
Everyone knew Kai's bark was about standards, never personal. He just took over the duties of Pat Rice. The old man, back in his more spry years, would have been shouting louder than Kai. The shout was a wake-up call, a reminder to treat training like match day.
And it worked. Over the next few drills, Mustafi's urgency shot up. He chased lost causes, snapped into tackles, and pushed through the fatigue as the tempo quickened.
Kai noticed. "That's better," he said with a curt nod. "That's how you adapt."
For Kai, attitude mattered as much as talent. Arsenal wasn't a club for passengers. Everyone here was chasing honours, fighting for the Champions League. There was no room for anyone just coasting.
Later, as the session wound down, Kai gave Mustafi a measured pat on the shoulder. "You did well. Still a bit vulnerable in the air—height will do that—but you're strong in the tackle alongside Laurent."
Mustafi managed a small smile, the sting of the earlier outburst fading. The team's style was starting to make sense.
Kai extended his hand, a grin breaking through. "Welcome to Arsenal again."
The others joined in with easy laughter.
"Mertesacker's going to feel the heat now!"
"Good shift, mate!"
"Welcome aboard!"
Looking around at the smiling faces, Mustafi realised something: they'd all been watching him, weighing his response. If he'd sulked or coasted after that scolding, he might never have truly been accepted.
Instead, he'd passed the test.
He clasped Kai's hand firmly, meeting the captain's eyes. "Thanks, Captain," he said, earnest and a little breathless.