In "The Duke of Detroit", Mike tries so hard to protect his gang that he doesn't worry about his own safety. It gets to the point that he's actually hindering them, and has to be convinced to let them fight their own battles for a change. The cherry on the heartwarming sundae is that he actually listens.
In "Texas-Ify It," the blink-and-you-miss-it moment of Texas' expression after seeing Mike preform the Texas Twister. He just looks so happy.
After Mike relates the events which made him desert Kane and continue to trouble him in the present in "Vendetta," Texas of all people gives him a surprisingly heartfelt pep-talk, in his own Texas-y way:
Texas: Ya gotta stop thinking about what you didn't do and start thinking about what you're doing to save people now! You can't change the past, unless you have a time machine.
Texas:(completely serious)Do you have a time machine?
It's subtle, but the way Julie's always there (especially in "Vendetta") to keep Mike's head in the game and help out is heartwarming.
Pretty much all of "Blond Thunder." Not only does Mike stake his own car in the wager with the Duke of Detroit without hesitation, but upon learning that Chuck doesn't even know how to drive, he takes it in stride and decides to teach Chuck how to drive himself. And dutifully does his job as a best friend by keeping that embarrassing knowledge to himself. When that doesn't pan out, he invokes Loophole Abuse to help Chuck win anyway. At the end of the episode, his only condition as Secret Keeper is that Chuck continue taking driving lessons from him. Well, that and the agreement that Chuck never drives Mutt. That, friends, is True Companionship.
Not to mention how he promptly goes looking for the missing piece to Chuck's car as soon as he finds out Chuck doesn't have one, and goes through quite a bit of trouble in the process.
"Going Dutch" basically cements Mike's role as the mama bird of the group just by how he recognizes that Dutch needs a break and is more than happy to give it to him.
"Ride of the Fantasy Vans" showcases how much Mike and Chuck look out for each other, particularly with the ending.
"You're no Miss Deluxe, you're a BURNER, lady!"
While the others were snapping at her about spending too much time in Deluxe, Mike never once joins in and continues to defend her, and is also very concerned with her safety all the while. Later, when she's being controlled by her suit and fighting Mike on the way to be delivered to Kane, she tells him to leave her because Motorcity needs him. He immediately fires back that he's not leaving her and that Motorcity needs her, too.
"Like Father, Like Daughter" shows that Kane really does care about Julie, in his own twisted way, and even shows that he believes and trusts in her enough to name her his successor to lead Deluxe in case something happens to him.
In "Mayhem Night," after an episode of distrust, Bracket comes to terms with Tennie and Dutch's relationship and even invites Dutch over for dinner.
Mike trying to get through to Chuck when the latter is using the booster.
Pretty much any moment with Dutch and Tennie.
"And you know what? They make Julie happy! So I guess that makes them my friends, too!"
The ending of "Reunion" in which Dar covers all of his Kane posters with drawings he and Dutch made. Also, this nice scene:
Dutch: Listen, I know I didn't leave on the best of terms and I wanted to call but I didn't want to cause any trouble for you and I didn't know how you felt about everything or if you were mad-
*Dutch's father hugs him*
Dutch: Man, it's good to see you guys.
Mike calls Chuck a genius in "Vega" and Chuck is clearly flattered.
On that note, Mike's talk with Julie. If "Off the Rack" didn't indicate how completely he trusts her, this episode did.
Pretty much all of the time Mike and Julie spend with each other in "A Better Tomorrow." Kudos to the writers for making them close friends without feeling the need to make them a couple.