Shepard didn't just turn herself into the Alliance after taking down the Collectors.
Grunt went along refusing to leave his 'Battlemaster' alone therefore the Alliance has to deal with a teenaged Krogan who is determined to keep his 'mother' safe.
Cue Kaidan. Grunt knows of Kaidan - maybe he was on the team when Shepard went to Horizon and is not very pleased with Shepard's 'Mate' hurting her.
Kaidan is trying to get to Shepard to apologise - you could have that someone *CoughMordinCough* sent him detailed reports of Cerberus rebuilding Shepard - but Grunt isn't allowing it to happen.

Kaidan and Grunt having a face-off with Shepard oblivious and James taking bets on who would be the winner.

It doesn't need to be too serious. In my headcannon, Grunt is my Shepard's baby boy since she was the one to 'birth' him, not to mention he took lessons from her in how to be a badass so I can't see Grunt being too happy about Kaidan wanting to be near Shepard again.

"No!" Vega cautiously peeked around the corner while lying on the floor, with other Alliance personnel above him watching. Now was the moment of truth, would Grunt stand down or would the Major be turned into a nice smear on the wall. Currently the Krogan, Grunt was standing in front of the door, arms folded and snarling at the human in front of him, mimicking his posture. Brow drawn in a furrow and lips in a frown. Major Commander Alenko and Urdnot Grunt were now engaged in a stand off.

"Grunt, Let me in to see Commander Shepard. I want to apologise to her."

"No." Came the simple reply. Everyone held their breath as Alenko took a step forward.

"Have you thought about asking your Battle-master if she would like to see me?"

"No. You are not worthy to see my Battle-master." Growled Grunt. "Not after what you did on Horizon." Alenko wearily rubbed his forehead.

"That's what I want to apologise about. I am admitting 'Battle Master' Shepard was right and that I shouldn't have shouted at her." Vega was distracted by somebody passing him some money and mouthing 'fifty creds on the Krogan.' James nodded and returned his attention to the stand off. Everyone could tell this had been coming. The Krogan had insisted on accompanying Commander Shepard to her trial and that Kaidan had been requesting to see Shepard. The higher-ups had finally allowed it, only if he could get past the Krogan standing guard ,day and night, in front of Shepard's door. Only Anderson and Vega could get past.

"No." Grunt gave the Major a shove, but Alenko still held his ground. "Hmph. You're just as stubborn as Shepard."

"Which is why it'll be easier to let me in now instead of later."

"Nice try, weakling." The brow furrowed even more.

"I fought alongside Shepard, I am not weak." The words came out in a low growl. Grunt leaned his head forward till their foreheads were touching, surprisingly Alenko didn't flinch.

"Yes you are. You're flawed. Shepard is not. Flawed human has no chance against the pure Krogan."

"Really? Ever heard of David and Goliath?"

"Stupid fairytale. Now get lost."

"No." Replied Kaidan simply. That was when Grunt lost his temper and grabbed Alenko by the collar and hoisted him up in the air. There was a flicker of panic in the Major's eyes, but then they narrowed as if he was focusing.

There was a flash of blue as the Major flared his biotics and biotic headbutted the young Krogan. He was dropped and landed on his feet as Grunt stumbled backwards in surprise. Blue eyes wide with dismay. The Krogan growled and advanced on Kaidan, who still stood his ground.

"You...You dare?" The look Alenko gave him answered the question. Grunt's eyes widened as he thought about this new development. He stepped forward grinning so his tombstone teeth were visible and pulled Alenko into a brotherly hug. "Okay! You're worthy. But don't come running to me like a Pyjak if Shepard kicks your ass."

As the Major entered Shepard's room, everyone grumbled as they lost their money to those few who'd bet Alenko would get pass. In fact Anderson walked away a very rich man. Though now another pool started up.

Would Alenko would walk out alive of Shepard's room?