- It's really cool to see how the Turtles ultimately end up bonding with Batman and the rest of the Bat-family.
- Donnie becomes close to Barbara Gordon (aka, "Batgirl"), who serves as the "April O'Neil" for the movie. Donnie and Batgirl are the ones who ultimately create the anti-ooze (what Donnie calls it)/retromutagen (what Batgirl prefers to call it) and just after creating it, Batgirl asks if the genius-turtle is okay with her calling him "Donnie" instead of "Donatello," to which he assures that he's fine with.
- Raph and Mikey end up bonding with Damian Wayne (the current Robin). While the three are fighting off Mr. Freeze in Arkham Asylum after all the inmates have mutated with the ooze/mutagen, Robin gets hurt at one point and both Raph and Mikey do their best to try and protect him. Also, after Batman's been returned to normal after having been mutated by a fusion of the Joker Venom and the TCRI-ooze, Robin thanks Mikey for doing so (as he was the one who was ultimately able to inject it into Batman). Mikey ends up grabbing the Boy Wonder into a big Bear Hug.
- Leo ends up bonding with Batman himself, and shortly after meeting the Turtles in person (after they successfully infiltrated the Batcave), Leo and Batman are doing a little sparring practice, and Batman compliments Leo's skills, noting that Master Splinter (the Turtles' dad) would be very proud of him.
- When Batman and the turtles start to have a falling-out after what happened at Arkham, Raph is the one who steps up and convinces Batman they need to work together, explaining how he also gets annoyed by his brothers but going solo always gets him into more trouble.Raph: We're a family, and learning from your mistakes together is how a family works.
Batman: This isn't a family, it's a team.
Raph: Ain't that the same thing?
(Batman is silent for a moment, looking back at Robin, Batgirl, and Alfred)
Batman: You're right. Let's stop Ra's and Shredder... together.
- At the end of the movie, once the whole adventure is over and turtles are getting ready to go back home to New York City, Batman decides to hold a goodbye for them and orders pizza for everyone—Batman even ends up joining in on it as well by handing a slice to Robin and grabbing one for himself.
Batgirl: My handle online is, "Oracle". (Donnie smiles and silently sends her a message from his communicator) Oh, I see you. Bo-staffs are... cool.
- Batgirl and Donnie end up exchanging contact information so they can still keep in touch.
- Joker and Harley Quinn, who are normally known to have a.... dysfunctional relationship, are surprisingly wholesome to one another throughout the movie — a rarity for the two in any medium.
Heartwarming / Batman vs. The Teenage Mutant Ninja Turtles